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Hire Richard M.

United Kingdom

USD 60 /hr

Freelance Data Analyst | 15+ years of experience in imaging and time-series data | ML/AI Expert | Python and R |

Profile Summary

I am a professor and world leading expert in Solar Physics, obtaining my PhD in 2011 and working in the field for 15+ years. My domain expertise cover magnetohydrodynamics, waves, solar/astrophysics, analysis of time-series and imaging data, signal processing, and probabilistic modelling. I have over 15 years of experience in hands-on work with a variety of data sets from different satellites and telescopes to understand physical processes. I have developed the following competencies: • Signal Extraction: Extracting meaningful signals from noisy, complex datasets. • Ground Truth Verification: Verifying physical constraints and mathematical accuracy in theoretical models. • Data Evaluation: Mapping observational data to physical phenomena to ensure theoretical consistency. • Technical Synthesis: Aggregating data and literature into cohesive, fact-based summaries or conclusions. And I have a skill set that includes: • Mathematics/Physics: Magnetohydrodynamics, Plasma, Astrophysics, PDEs, Bayesian Statistics, Time-series Analysis, Fourier, Wavelets, Regression/Classification, Machine Learning. • Programming: Python (e.g., NumPy, SciPy, Pandas, Matplotlib), R, IDL, Matlab. My results are shared with audiences from a variety of backgrounds. I also devise and teach on the undergraduate and Masters Mathematics and Physics programmes. Hence, I am confident in articulating complex technical concepts and reasoning to non-experts.

Subject Matter Expertise

• ★ Data Analysis
• ☆ Image Processing
• ☆ Computer Simulation/Computational Modeling
• ☆ Predictive Modeling & Analytics
• ☆ Data Processing
• ☆ Data Exploration
• ☆ Cluster Analysis
• ☆ Data Visualization
• ☆ Data Manipulation
• ☆ Machine Learning
• ☆ Data Cleaning
• ☆ Neural Networks
• ☆ Pattern Recognition
• ☆ Artificial Intelligence
• ☆ Deep Learning
• ☆ Computer Vision
• ☆ Statistics
• ☆ Applied Statistics
• ☆ Regression Analysis
• ☆ Multivariate Analysis
• ☆ Nonlinear Regression
• ☆ Bayesian Statistics
• ☆ Correlation Analysis
• ☆ Astrophysics
• ☆ Wave Mechanics
• ☆ Applied Physics
• ☆ Plasma Physics
• ☆ Astronomy
• ☆ Applied Mathematics
• ☆ Mathematical Physics
• ☆ Differential Equations

Services

• Research
• Consulting
• Data & AI

Research Technology Scouting, Fact Checking, Scientific and Technical Research, Systematic Literature Review

Consulting Scientific and Technical Consulting

Data & AI Predictive Modeling, Statistical Analysis, Image Processing, Image Analysis, Algorithm Design-Non ML, Algorithm Design-ML, Data Visualization, Data Cleaning, Data Processing, Data Insights

Work Experience

Northumbria University

- Present

Professor

Northumbria University

September 2025 - Present

UKRI Future Leader Fellow

Northumbria University

November 2020 - May 2028

Associate Professor

Northumbria University

November 2020 - September 2025

Senior Lecturer

Northumbria University

September 2017 - November 2020

Leverhulme Trust Early Career Fellow

Northumbria University

September 2014 - August 2017

Anniversary Research Fellow

Northumbria University

September 2012 - August 2014

Post-Doctoral Research Assistant

University of Sheffield

February 2011 - August 2012

Education

PhD Solar Physics

SHEFFIELD UNIVERSITY

September 2007 - February 2011

MPHYS Mathematics with Physics

Sheffield University (UK)

September 2003 - August 2007

Certifications

• Certification details not provided.

Publications

JOURNAL ARTICLE

R. J. Morton, Y. Gao, E. Tajfirouze, H. Tian, T. Van Doorsselaere, T. A. Schad (2025). Evidence for small-scale torsional Alfvén waves in the solar corona . Nature Astronomy.

Evidence for small-scale torsional Alfvén waves in the solar corona @article{c522246c0151499eaf3316317ef1fbd8, title = "Evidence for small-scale torsional Alfv{\'e}n waves in the solar corona", abstract = "The corona is the outer layer of the Sun{\textquoteright}s atmosphere. Its plasma is accelerated, flowing out into interplanetary space as a heated, supersonic wind. The details of energy and momentum transfer to the plasma remain debated. Alfv{\'e}n waves are a favoured mechanism and, in a plasma composed of inhomogeneous flux tubes, the only pure Alfv{\'e}n mode is torsional in nature. Large-scale modes have been observed sporadically but a prevalent, small-scale counterpart in the corona has yet to be established. The Daniel K. Inouye Solar Telescope has begun to provide unprecedented views of the Sun, with the Cryo-NIRSP instrument delivering high spatial and spectral resolution coronal observations. The data reveal that the quiescent corona supports torsional Alfv{\'e}n waves, continuously twisting the magnetic field lines back and forth. Measured wave amplitudes are small but are likely underestimated due to line-of-sight integration. The results suggest the waves may carry a significant fraction of the energy required to power the quiet Sun and solar wind.", author = "R.J. Morton and Y. Gao and E. Tajfirouzeh and H. Tian and \{Van Doorsselaere\}, T. and T.A. Schad", year = "2025", month = oct, day = "24", doi = "10.1038/s41550-025-02690-9", language = "English", pages = "1--17", journal = "Nature Astronomy", issn = "2397-3366", publisher = "Nature Publishing Group", } . Nature Astronomy.

Richard J. Morton, Roberto Soler (2025). On the Origins of Coronal Alfvénic Waves . The Astrophysical Journal Letters.

On the origins of coronal Alfvénic waves @article{db62961c5b4943bab5ddedaa17bf9eb6, title = "On the origins of coronal Alfv{\'e}nic waves", abstract = "Alfv{\'e}nic waves are considered a key contributor to the energy flux that powers the Sun's corona, with theoretical models demonstrating their potential to explain coronal EUV and X-ray emission and the acceleration of the solar wind. However, confirming underlying assumptions of the models has proved challenging, especially obtaining evidence for the excitation and dissipation of Alfv{\'e}nicc waves in the lower solar atmosphere and tracing their propagation into the corona. We present an investigation of the Alfv{\'e}nic wave power spectrum in the Sun{\textquoteright}s corona, obtained from observations with DKIST Cryo-NIRSP. The data provide unprecedented temporal resolution and signal-to-noise, revealing a detailed power spectrum out to frequencies exceeding 10 mHz. A broad enhancement in power dominates the spectrum and we demonstrate it is accurately reproduced using a physics-based model. The results corroborate the scenario where the corona is dominated by Alfv{\'e}nic waves excited in the photosphere by horizontal convective motions, with low-frequency waves subject to reflection at the transition region and higher frequency waves significantly dissipated by the partially ionized chromosphere. The coronal Alfv{\'e}nic power spectrum also indicates there are contributions from p-modes (via mode conversion) and a yet-unknown higher-frequency source. These results provide key insight into how the Sun{\textquoteright}s convective motions imprint themselves on the corona and highlight the critical role of partial ionization, reflection, and damping in regulating upward-propagating Alfv{\'e}nic waves. A further implication of this is that reconnection-driven Alfv{\'e}nic waves likely play a smaller role in powering the corona and solar wind than has been suggested by recent studies.", keywords = "Alfven waves, Magnetohydrodynamics, Solar corona, Solar coronal waves", author = "Richard Morton and Roberto Soler", year = "2025", month = jun, day = "3", doi = "10.3847/2041-8213/add7da", language = "English", volume = "986", journal = "Astrophysical Journal Letters", issn = "2041-8205", publisher = "American Astronomical Society", number = "1", } . Astrophysical Journal Letters.

R. J. Morton, M. J. Weberg, N. Balodhi, J. A. McLaughlin (2025). Estimating the Poynting Flux of Alfvénic Waves in Polar Coronal Holes across Solar Cycle 24 . The Astrophysical Journal.

Estimating the Poynting flux of Alfvenic waves in polar coronal holes across Solar Cycle 24 @article{a86bd28537f146c09c923c9cbe6616b4, title = "Estimating the Poynting flux of Alfvenic waves in polar coronal holes across Solar Cycle 24", abstract = "Alfvenic waves are known to be prevalent throughout the corona and solar wind. Determining the Poynting flux supplied by the waves is required for constraining their role in plasma heating and acceleration, as well as providing a constraint for Alfven wave driven models that aim to predict coronal and solar wind properties. Previous studies of the Alfvenic waves in polar coronal holes have been able to provide a measure of energy flux for arbitrary case studies. Here we build upon previous work and take a more systematic approach, examining if there is evidence for any variation in vertical Poynting flux over the course of the solar cycle. We use imaging data from SDO/AIA to measure the displacements of the fine-scale structure present in coronal holes. It is found that the measure for vertical Poynting flux is broadly similar over the solar cycle, implying a consistent contribution from waves to the energy budget of the solar wind. There is variation in energy flux across the measurements (around 30\%), but this is suggested to be due to differences in the individual coronal holes rather than a feature of the solar cycle. Our direct estimates are in agreement with recent studies by Huang et. al. (2023, 2024) who constrain the vertical Poynting flux through comparison of predicted wind properties from Alfvenic wave driven turbulence models to those observed with OMNI at 1\textasciitilde{}AU. Taken together, both sets of results points towards a lack of correlation between the coronal Poynting flux from waves and the solar cycle. ", author = "Morton, \{R. J.\} and Weberg, \{M. J.\} and N. Balodhi and McLaughlin, \{J. A.\}", year = "2025", month = may, day = "20", doi = "10.48550/arXiv.2501.13673", language = "English", volume = "958", pages = "1--12", journal = "Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . Astrophysical Journal.

Wave analysis tools @article{7dd7480d1d32427da40cf6dca81170bb, title = "Wave analysis tools", abstract = "This Primer provides an overview of a fundamental set of analysis methods for studying waves, vibrations and related oscillatory phenomena — including instabilities, turbulence and shocks — across diverse scientific fields. These phenomena are ubiquitous, from astrophysics to complex systems in terrestrial environments, and understanding them requires careful selection of techniques. Misapplication of analysis tools can introduce misleading results. In this Primer, the fundamental principles of various wave analysis methods are first reviewed, along with adaptations to address complexities such as nonlinear, non-stationary and transient signal behaviour. These techniques are applied to identical synthetic datasets to provide a quantitative comparison of their strengths and limitations. Details are provided to help select the most appropriate analysis tools based on specific data characteristics and scientific goals, promoting reliable interpretations and ensuring reproducibility. Additionally, the Primer highlights best ethical practices for data deposition and the importance of open-code sharing. Finally, the broad applications of these techniques are explored in various research fields, current challenges in wave analysis are discussed, and an outlook on future directions is provided, with an emphasis on potential transformative discoveries that could be made by optimizing and developing cutting-edge analysis methods.", author = "Shahin Jafarzadeh and Jess, \{David B.\} and Marco Stangalini and Grant, \{Samuel D.T.\} and Higham, \{Jonathan E.\} and Pessah, \{Martin E.\} and Keys, \{Peter H.\} and Sergey Belov and Daniele Calchetti and Duckenfield, \{Timothy J.\} and Viktor Fedun and Bernhard Fleck and Ricardo Gafeira and Jefferies, \{Stuart M.\} and Elena Khomenko and Morton, \{Richard J.\} and Norton, \{Aimee A.\} and Rajaguru, \{S. P.\} and Schiavo, \{Luiz A.C.A.\} and Rahul Sharma and Silva, \{Suzana S.A.\} and Solanki, \{Sami K.\} and Oskar Steiner and Gary Verth and Gangadharan Vigeesh and Nitin Yadav", note = "Publisher Copyright: {\textcopyright} Springer Nature Limited 2025.", year = "2025", month = apr, day = "3", doi = "10.1038/s43586-025-00392-0", language = "English", volume = "5", journal = "Nature Reviews Methods Primers", issn = "2662-8449", publisher = "Springer", number = "1", } . Nature Reviews Methods Primers.

Determining the Polarization of a Coronal Standing Kink Oscillation Using Spectral Imaging Techniques with CoMP @article{ac0139e563754183971b6b6b4e03966e, title = "Determining the Polarization of a Coronal Standing Kink Oscillation Using Spectral Imaging Techniques with CoMP", abstract = "Coronal oscillations offer insight into energy transport and driving in the solar atmosphere. Knowing its polarization state helps constrain a wave{\textquoteright}s displacement and velocity amplitude, improving estimates of wave energy flux and deposition rate. We demonstrate a method to combine imaging and spectral data to infer the polarization of a coronal loop{\textquoteright}s standing kink wave, without the need for multiple instruments or multiple lines of sight. We use the unique capabilities of the Coronal Multi-channel Polarimeter (CoMP) to observe the standing kink mode of an off-limb coronal loop perturbed by an eruption. The full off-disk corona is observed using the 1074 nm Fe xiii spectral line, providing Doppler velocity, intensity, and line width. By tracking the oscillatory motion of a loop apex in a time–distance map, we extract the line-of-sight (Doppler) velocity of the inhomogeneity as it sways and compare it with the derivative of its plane-of-sky displacement. This analysis provides the loop{\textquoteright}s velocity in two perpendicular planes as it oscillates with a period of 8.9−0.5+0.5 minutes. Through detailed analysis of the phase relation between the transverse velocities, we infer the kink oscillation to be horizontally polarized, oscillating in a plane tilted −13.°6−3.0+2.9 away from the plane of sky. The line widths show a periodic enhancement during the kink oscillation, exhibiting both the kink period and its double. This study is the first to combine direct imaging and spectral data to infer the polarization of a coronal loop oscillation from a single viewpoint.", keywords = "Infrared spectroscopy, Solar coronal seismology, Active solar corona, Solar oscillations", author = "T.J. Duckenfield and D.B. Jess and R.J. Morton and S. Jafarzadeh", year = "2025", month = apr, day = "1", doi = "10.3847/1538-4357/adb8d6", language = "English", volume = "982", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . The Astrophysical Journal.

Richard Morton, Edris Tajfirouze, Mahboubeh Asgari-Targhi (2025). Turbulent Suppression of Alfvénic Wave Resonances in Coronal Loops . The Astrophysical Journal.

T. J. Duckenfield, D. B. Jess, R. J. Morton, S. Jafarzadeh (2025). Determining the Polarization of a Coronal Standing Kink Oscillation Using Spectral Imaging Techniques with CoMP . The Astrophysical Journal.

Richard J. Morton, Momchil Molnar, Steven R. Cranmer, Thomas A. Schad (2025). High-frequency Coronal Alfvénic Waves Observed with DKIST/Cryo-NIRSP . The Astrophysical Journal.

High-frequency coronal Alfvénic waves observed with DKIST/Cryo-NIRSP @article{6152547f0dfe41f891af21e05ef9041f, title = "High-frequency coronal Alfv{\'e}nic waves observed with DKIST/Cryo-NIRSP", abstract = "The presence and nature of low-frequency (0.1-10\textasciitilde{}mHz) Alfv\textbackslash{}'enic waves in the corona has been established over the last decade, with many of these results coming from coronagraphic observations of the infrared Fe XIII line. The Cryo-NIRSP instrument situated at DKIST has recently begun acquiring science quality data of the same Fe XIII line, with at least a factor of 9 improvement in spatial resolution, a factor 30 increase in temporal resolution and an increase in signal-to-noise, when compared to the majority of previously available data. Here we present an analysis of 1\textasciitilde{}s cadence sit-and-stare data from Cryo-NIRSP, examining the Doppler velocity fluctuations associated with the Fe XIII 1074\textasciitilde{}nm coronal line. We are able to confirm previous results of Alfv\textbackslash{}'enic waves in the corona as well as explore a new frequency regime. The data reveals that the power law behaviour of the Doppler velocity power spectrum extends to higher frequencies. This result appears to challenge some models of photospheric-driven Alfv\textbackslash{}'enic waves that predict a lack of high frequency wave power in the corona due to strong chromospheric damping. Moreover, the high-frequency waves do not transport as much energy as their low-frequency counterparts, with less time-averaged energy per frequency interval. We are also able to confirm the incompressible nature of the fluctuations with little coherence between the line amplitude and Doppler velocity time-series. ", keywords = "Alfven waves, Magnetohydrodynamics, Infrared spectroscopy, Solar corona, Solar coronal waves", author = "Morton, \{Richard J.\} and Momchil Molnar and Cranmer, \{Steven R.\} and Schad, \{Thomas A.\}", year = "2025", month = mar, day = "21", doi = "10.48550/arXiv.2501.03758", language = "English", volume = "982", pages = "1--21", journal = "Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . Astrophysical Journal.

Richard Morton, Edris Tajfirouze, Peter R. Young (2025). Hinode/EIS Observation of the Alfvénic Fluctuations in the Quiet Sun . The Astrophysical Journal.

Turbulent suppression of Alfvénic wave resonances in coronal loops @article{c4c2b600e8db46b89bb1a45a5e3b8fba, title = "Turbulent suppression of Alfv{\'e}nic wave resonances in coronal loops", abstract = "Alfv{\'e}nic wave turbulence is a leading mechanism for explaining the heating of the solar corona and the acceleration of the solar wind. Alfv{\'e}nic waves are observed to be prevalent throughout the inner corona. An intriguing aspect of the observed waves is that active-region loops show decayless standing Alfv{\'e}nic oscillations, while quiet-Sun loops show only propagating Alfv{\'e}nic waves. Given the weaker rates of resonant damping found in the quiet Sun (compared to those estimated from decaying oscillations of active-region loops), the reason for the lack of observed standing oscillations is unclear. We suggest that this may be due to the presence of efficient (or strong) Alfv{\'e}nic wave turbulence in the quiet Sun, which limits the ability of waves to form resonant oscillations in the coronal cavity. To test this idea, we model the coronal velocity fluctuations using a previously developed 3D reduced magnetohydrodynamic model. In this model, we implement a semi-realistic profile for atmospheric plasma conditions along the magnetic field and a homogeneous plasma perpendicular to the magnetic field. Results are presented for different models of the background atmosphere that effectively have different levels of coronal turbulence. For the Alfv{\'e}nic waves in the simulation, we see that resonant modes are present when the coronal turbulence is in a weak regime. However, decreasing the nonlinear timescale leads to a faster development of turbulence. This can suppress the presence of standing modes when the nonlinear timescale is comparable to or shorter than the Alfv{\'e}n travel time.", author = "Richard Morton and Edris Tajfirouzeh and Mahboubeh Asgari-Targhi", year = "2025", month = mar, day = "20", doi = "10.3847/1538-4357/adb48b", language = "English", volume = "982", journal = "Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . Astrophysical Journal.

Hinode/EIS Observation of the Alfvénic Fluctuations in the Quiet Sun @article{9ead5f598f3a46419e5b27ed252d21cf, title = "Hinode/EIS Observation of the Alfv{\'e}nic Fluctuations in the Quiet Sun", abstract = "Alfv{\'e}nic fluctuations in the corona are regularly observed in EUV imaging and infrared spectroscopic data. We report here on the Doppler velocity fluctuations within the data from the Extreme-Ultraviolet Imaging Spectrometer (EIS) on board Hinode. The capabilities of EIS provide an opportunity to detect fluctuations in the solar atmosphere and confirm the previous results from ground-based spectroscopic data using EIS{\textquoteright}s EUV spectra and in seeing-free conditions. We analyzed Doppler velocity time series for a particular date of observation, 2007 September 27, above the limb. The Fourier transform of the observed signals show the Doppler velocity has a broad spectrum distributed as a power law with a power enhancement around 3–4 mHz. This result is consistent with previous observational results obtained with Coronal Multi-Channel Polarimeter data, and hence we interpret the Doppler velocity fluctuations as Alfv{\'e}nic in nature. We performed nonlinear regression on the power spectra to determine the index of the power law and to parameterize the properties of the enhancement. We find good agreement between the estimated values and those from previous studies. Furthermore, correlation analysis shows that the observed oscillations are spatially coherent perpendicular to the magnetic field on the length scale L⊥ ∼ 8 Mm, providing an estimate on the energy injection scale of a bundle of coherently oscillating loops.", keywords = "Solar oscillations, Quiet solar corona", author = "Edris Tajfirouze and Richard Morton and Young, \{Peter R.\}", year = "2025", month = mar, day = "19", doi = "10.3847/1538-4357/adb9e5", language = "English", volume = "982", pages = "1--7", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

The coronal power spectrum from MHD mode conversion above sunspots @article{b34179d3a5a64a4c909938b656d9e3a5, title = "The coronal power spectrum from MHD mode conversion above sunspots", abstract = "Sunspots are intense regions of magnetic flux that are rooted deep below the photosphere. It is well established that sunspots host magnetohydrodynamic waves, with numerous observations showing a connection to the internal acoustic (or p-)modes of the Sun. The p-modes are fast waves below the equipartition layer and are thought to undergo a double mode conversion as they propagate upwards into the atmosphere of sunspots, which can generate Alfv{\'e}nic modes in the upper atmosphere. We employ 2.5D magnetohydrodynamics (MHD) numerical simulations to investigate the adiabatic wave propagation and examine the resulting power spectra of coronal Alfv{\'e}nic waves. A broadband wave source is used that has a 1D power spectrum which mimics aspects of the observed p-mode power spectrum. We examine magnetoacoustic wave propagation and mode conversion from the photosphere to the corona. Frequency filtering of the upwardly propagating acoustic waves is a natural consequence of a gravitationally stratified atmosphere, and plays a key role in shaping the power spectra of mode converted waves. We demonstrate that the slow, fast magnetoacoustic waves and Alfv{\'e}n waves above the equipartition layer have similarly shaped power spectra, which are modified versions of the driver spectrum. Notably, the results reveal that the coronal wave power spectra have a peak at a higher frequency than that of the underlying p-mode driver. This matches observations of coronal Alfv{\'e}nic waves and further supports the role of mode conversion process as a mechanism for Alfv{\'e}nic wave generation in the Sun's atmosphere.", author = "Hemanthi Miriyala and Richard Morton and Elena Khomenko and Patrick Antolin and Gert Botha", year = "2025", month = feb, day = "1", doi = "10.3847/1538-4357/ada26f", language = "English", volume = "979", journal = "Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . Astrophysical Journal.

Hemanthi Miriyala, Richard J. Morton, Elena Khomenko, Patrick Antolin, Gert J.J. Botha (2025). The Coronal Power Spectrum from MHD Mode Conversion above Sunspots . The Astrophysical Journal.

Zihao Yang, Hui Tian, Steven Tomczyk, Xianyu Liu, Sarah Gibson, Richard J. Morton, Cooper Downs (2024). Observing the evolution of the Sun’s global coronal magnetic field over 8 months . Science.

Observing the evolution of the Sun’s global coronal magnetic field over 8 months @article{759f6a75073b4a29b5c1149ab73dc260, title = "Observing the evolution of the Sun{\textquoteright}s global coronal magnetic field over 8 months", abstract = "The magnetic field in the Sun{\textquoteright}s corona stores energy that can be released to heat plasma and drive solar eruptions. Measurements of the global coronal magnetic field have been limited to several snapshots. In this work, we present observations, using the Upgraded Coronal Multi-channel Polarimeter, that provide 114 magnetograms of the global corona above the solar limb spanning \textasciitilde{}8 months. We determined the magnetic field distribution with altitude in the corona and monitored the evolution at different latitudes over multiple solar rotations. The field strength between 1.05 and 1.60 solar radii varies from <1 to \textasciitilde{}20 gauss. A signature of active longitudes appears in the coronal magnetic field measurements. Coronal models are generally consistent with our observations, though they have larger discrepancies in high-latitude regions.", author = "Zihao Yang and Hui Tian and Steven Tomczyk and Xianyu Liu and Sarah Gibson and Morton, \{Richard J.\} and Cooper Downs", year = "2024", month = oct, day = "4", doi = "10.1126/science.ado2993", language = "English", volume = "386", pages = "76--82", journal = "Science", issn = "0036-8075", publisher = "American Association for the Advancement of Science", number = "6717", } . Science.

Sausage, kink, and fluting magnetohydrodynamic wave modes identified in solar magnetic pores by Solar Orbiter/PHI @article{ce5c400978af4ac48239c136a203d8d7, title = "Sausage, kink, and fluting magnetohydrodynamic wave modes identified in solar magnetic pores by Solar Orbiter/PHI", abstract = "Solar pores are intense concentrations of magnetic flux that emerge through the solar photosphere. When compared to sunspots, they are much smaller in diameter and can therefore be affected and buffeted by neighbouring granular activity to generate significant magnetohydrodynamic (MHD) wave energy flux within their confines. However, observations of solar pores from ground-based telescope facilities may struggle to capture subtle motions that are synonymous with higher-order MHD wave signatures because of the seeing effects that are produced in the Earth's atmosphere. Hence, we exploited timely seeing-free and high-quality observations of four small magnetic pores from the High Resolution Telescope (HRT) of the Polarimetric and Helioseismic Imager (PHI) on board the Solar Orbiter spacecraft during its first close perihelion passage in March 2022 (at a distance of 0.5 au from the Sun). Through acquisition of data under stable observing conditions, we were able to measure the area fluctuations and horizontal displacements of the solar pores. Cross correlations between perturbations in intensity, area, line-of-sight velocity, and magnetic fields, coupled with the first-time application of novel proper orthogonal decomposition techniques on the boundary oscillations, provided a comprehensive diagnosis of the embedded MHD waves as sausage and kink modes. Additionally, the previously elusive m = 2 fluting mode is identified in the most magnetically isolated of the four pores. An important consideration lies in how the identified wave modes contribute to the transfer of energy into the upper solar atmosphere. Approximately 56\%, 72\%, 52\%, and 34\% of the total wave energy of the four pores we examined is associated with the identified sausage modes and about 23\%, 17\%, 39\%, and 49\% with their kink modes, while the first pore also receives a contribution of about 11\% linked to the fluting mode. This study reports the first-time identification of concurrent sausage, kink, and fluting MHD wave modes in solar magnetic pores.", keywords = "Magnetohydrodynamics (MHD), Sun: magnetic fields, Sun: oscillations, Sun: photosphere", author = "S. Jafarzadeh and Schiavo, \{L. A.C.A.\} and V. Fedun and Solanki, \{S. K.\} and M. Stangalini and D. Calchetti and Gary Verth and Jess, \{D. B.\} and Grant, \{S. D.T.\} and I. Ballai and R. Gafeira and Keys, \{P. H.\} and B. Fleck and Morton, \{R. J.\} and Browning, \{P. K.\} and Silva, \{Suzana S.A.\} and T. Appourchaux and A. Gandorfer and L. Gizon and J. Hirzberger and F. Kahil and \{Orozco Su{\'a}rez\}, D. and J. Schou and H. Strecker and \{Del Toro Iniesta\}, \{J. C.\} and G. Valori and R. Volkmer and J. Woch", year = "2024", month = aug, day = "1", doi = "10.1051/0004-6361/202449685", language = "English", volume = "688", journal = "Astronomy and Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", } . Astronomy and Astrophysics.

Can the Solar p-modes Contribute to the High-frequency Transverse Oscillations of Spicules? @article{8a5a4baaf9024603aea5627759d9ee30, title = "Can the Solar p-modes Contribute to the High-frequency Transverse Oscillations of Spicules?", abstract = "Lateral motions of spicules serve as vital indicators of transverse waves in the solar atmosphere, and their study is crucial for understanding the wave-heating process of the corona. Recent observations have focused on high-frequency transverse waves (periods < 100 s), which have the potential to transport sufficient energy for coronal heating. These high-frequency spicule oscillations are distinct from granular motions, which have much longer timescales of 5–10 minutes. Instead, it is proposed that they are generated through the mode conversion from high-frequency longitudinal waves that arise from a shock-steepening process. Therefore, these oscillations may not solely be produced by the horizontal buffeting motions of granulation but also by the leakage of p-mode oscillations. To investigate the contribution of p-modes, our study employs a two-dimensional magneto-convection simulation spanning from the upper convection zone to the corona. During the course of the simulation, we introduce a p-mode-like driver at the bottom boundary. We reveal a notable increase in the mean velocity amplitude of the transverse oscillations in spicules, ranging from 10\%–30\%, and attribute this to the energy transfer from longitudinal to transverse waves. This effect results in an enhancement of the estimated energy flux by 30\%–80\%.", keywords = "Radiative magnetohydrodynamics, Solar coronal heating, Solar spicules, Solar chromosphere, Solar oscillations", author = "Hidetaka Kuniyoshi and Munehito Shoda and Morton, \{Richard J.\} and Takaaki Yokoyama", note = "Funding information: We would like to convey our sincere appreciation to the anonymous referee for providing valuable feedback. Numerical computations were carried out on the Cray XC50 at the Center for Computational Astrophysics (CfCA), National Astronomical Observatory of Japan. M.S. is supported by JSPS KAKENHI grant No. JP22K14077. R.J.M. is supported by a UKRI Future Leader Fellowship (RiPSAW MR/T019891/1). H.K. is also grateful for travel support provided by the UKRI Future Leader Fellowship (RiPSAW MR/T019891/1). T.Y. is supported by JSPS KAKENHI grant Nos. JP21H01124, JP20KK0072, and JP21H04492. This work was supported by the NAOJ Research Coordination Committee, NINS, grant No. NAOJ-RCC-2301-0301.", year = "2024", month = jan, day = "10", doi = "10.3847/1538-4357/ad1038", language = "English", volume = "960", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . The Astrophysical Journal.

Hidetaka Kuniyoshi, Munehito Shoda, Richard J. Morton, Takaaki Yokoyama (2024). Can the Solar p-modes Contribute to the High-frequency Transverse Oscillations of Spicules? . The Astrophysical Journal.

Kuniyoshi, H., Shoda, M., Morton, R.J., Yokoyama, T.(2024). Can the Solar p-modes Contribute to the High-frequency Transverse Oscillations of Spicules? . Astrophysical Journal. 960. (2).

Transverse energy injection scales at the base of the solar corona @article{f1a05446759246e59c20fddd8eb13265, title = "Transverse energy injection scales at the base of the solar corona", abstract = "Alfv{\'e}n wave turbulence models lie at the heart of many investigations into the winds and extreme-ultraviolet and X-ray emission from cool, solar-like stars. The models provide insights into mass loss, magnetic spin down and exoplanet habitability. Yet they currently rely on ad hoc estimates of critical parameters. One critical but unknown parameter is the perpendicular correlation length, which controls the turbulent heating rate and, hence, has a role in determining the properties of coronal plasma. Here, using the Coronal Multi-channel Polarimeter, we measure the correlation length of Alfv{\'e}nic waves at the base of the corona. The measurements are an order of magnitude closer to the Sun than previous estimates for the perpendicular correlation length. Our analysis shows the values are broadly homogeneous through the corona and have a distribution sharply peaked around 7.6–9.3 Mm. The measured correlation length is comparable to the expected scales associated with supergranulation. The results provide a stringent constraint for Alfv{\'e}n wave turbulence modelling.", author = "Rahul Sharma and Richard Morton", note = "Funding information: We are supported by a UKRI Future Leader Fellowship (RiPSAW-MR/T019891/1). We thank the CoMP, UCoMP and K-Cor instrument teams for providing the data used in this study. The CoMP, UCoMP and K-Cor instruments are located at the Mauna Loa Solar Observatory, operated by the High Altitude Observatory, as part of the National Center for Atmospheric Research (NCAR). NCAR is supported by the National Science Foundation. We also thank S. Cranmer for sharing numerical modelling data.", year = "2023", month = nov, day = "1", doi = "10.1038/s41550-023-02070-1", language = "English", volume = "7", pages = "1301--1308", journal = "Nature Astronomy", issn = "2397-3366", publisher = "Nature Publishing Group", number = "11", } . Nature Astronomy.

Rahul Sharma, Richard J. Morton (2023). Transverse energy injection scales at the base of the solar corona . Nature Astronomy.

R. J. Morton, R. Cunningham (2023). The Fine-scale Structure of Polar Coronal Holes . The Astrophysical Journal.

The Fine-scale Structure of Polar Coronal Holes @article{a41488b7273b4622b07f30ab2f87a109, title = "The Fine-scale Structure of Polar Coronal Holes", abstract = "Coronal holes are thought to be composed of relatively broad columnar structures known as plumes. Here, we demonstrate that the plumes (and interplumes) in polar coronal holes are composed of fine-scale filamentary structure, with average scales of 2″–10″. The fine structure is the off-limb analog of the previously found “plumelets” of Uritsky et al. The off-limb observations enable an examination of the fine structure without the influence of the underlying atmosphere along the line of sight. Hence, we show that the fine-scale structure is present at least until the edge of the field of view of the Solar Dynamics Observatory. The fine structure is found to have spatial distribution that follows a k −1 power law perpendicular to the inferred magnetic field direction. For a small sample of the fine structure, the cross-sectional profiles are measured as a function of height. In some cases, the measurements indicate that the fine structure expands super-radially, consistent with existing models of polar field expansion and the expansion of the plumes. We discuss the implications of the presence of the fine structure with respect to understanding wave propagation in the coronal holes and their contribution to powering the solar wind.", keywords = "Solar coronal plumes, Solar coronal holes, The Sun, Solar corona", author = "Morton, \{R. J.\} and Rosie Cunningham", note = "Funding information: R.J.M. is supported by a UKRI Future Leader Fellowship (RiPSAW MR/T019891/1). We would like to thank C. DeForest, P. Antolin, and N. Magyar for assistance and valuable discussions. Data used have been provided courtesy of NASA/SDO and the AIA, EVE, and HMI science teams. These data are freely available at http://jsoc.stanford.edu/. For the purpose of open access, the author(s) has applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising.", year = "2023", month = sep, day = "1", doi = "10.3847/1538-4357/acea7c", language = "English", volume = "954", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

Richard Morton, Patrick Antolin, Rahul Sharma, Alin Paraschiv, Edris Tajfirouze, Hui Tian, Steve Tomczyk, Zihao Yang (2023). Vol. 55, Issue 3 (Heliophysics 2024 Decadal Whitepapers) . Bulletin of the AAS.

Revealing the Sun’s Alfvénic waves @article{20d463822d9e44bd837c9bac3cec1569, title = "Revealing the Sun{\textquoteright}s Alfv{\'e}nic waves", abstract = "Alfv{\'e}nic waves are thought to be a key mechanism for energy transfer in the Sun{\textquoteright}s atmosphere. However, details of the waves journey from photosphere to corona to solar wind remain unverified. The Alfv{\'e}nic waves also offer the chance to explore the difficult to measure coronal magnetic field. New and future instrumentation will provide exciting opportunities to probe the Alfv{\'e}nic waves", keywords = "General Medicine, General Materials Science, Psychiatry and Mental health, Neuropsychology and Physiological Psychology, General Earth and Planetary Sciences, General Environmental Science, Pharmacology (medical), General Engineering", author = "Richard Morton and Patrick Antolin and Rahul Sharma and Alin Paraschiv and Edris Tajfirouze and Hui Tian and Steve Tomczyk and Zihao Yang", year = "2023", month = jul, day = "31", doi = "10.3847/25c2cfeb.3b4fe1c4", language = "English", volume = "55", pages = "1--10", journal = "Bulletin of the AAS", number = "3", } . Bulletin of the AAS.

The Role of High-frequency Transverse Oscillations in Coronal Heating @article{fc64851068e74e189760c3f7fcb064b1, title = "The Role of High-frequency Transverse Oscillations in Coronal Heating", abstract = "Transverse oscillations that do not show significant damping in solar coronal loops are found to be ubiquitous. Recently, the discovery of high-frequency transverse oscillations in small-scale loops has been accelerated by the Extreme Ultraviolet Imager on board Solar Orbiter. We perform a meta-analysis by considering the oscillation parameters reported in the literature. Motivated by the power law of the velocity power spectrum of propagating transverse waves detected with CoMP, we consider the distribution of energy fluxes as a function of oscillation frequencies and the distribution of the number of oscillations as a function of energy fluxes and energies. These distributions are described as a power law. We propose that the power-law slope (δ = −1.40) of energy fluxes depending on frequencies could be used for determining whether high-frequency oscillations dominate the total heating (δ < 1) or not (δ > 1). In addition, we found that the oscillation number distribution depending on energy fluxes has a power-law slope of α = 1.00, being less than 2, which means that oscillations with high energy fluxes provide the dominant contribution to the total heating. It is shown that, on average, higher energy fluxes are generated from higher-frequency oscillations. The total energy generated by transverse oscillations ranges from about 1020 to 1025 erg, corresponding to the energies for nanoflare (1024–1027 erg), picoflare (1021–1024 erg), and femtoflare (1018–1021 erg). The respective slope results imply that high-frequency oscillations could provide the dominant contribution to total coronal heating generated by decayless transverse oscillations.", keywords = "Solar coronal waves, Solar oscillations, Solar coronal heating", author = "Daye Lim and \{Van Doorsselaere\}, Tom and David Berghmans and Morton, \{Richard J.\} and Vaibhav Pant and Sudip Mandal", note = "Funding information: We are grateful to Hugh Hudson and the referee for constructive comments. We thank the NASA's Living With a Star Program, which SDO is part of, with the AIA instrument on board. Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA. The EUI instrument was built by CSL, IAS, MPS, MSSLUCL, PMODWRC, ROB, LCFIO with funding from the Belgian Federal Science Policy Office (BELSPO/PRODEX PEA C4000134088); the Centre National d'Etudes Spatiales (CNES); the UK Space Agency (UKSA); the Bundesministerium f{\"u}r Wirtschaft und Energie (BMWi) through the Deutsches Zentrum f{\"u}r Luft- und Raumfahrt (DLR); and the Swiss Space Office (SSO). T.V.D. was supported by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 724326), the C1 grant TRACEspace of Internal Funds KU Leuven, and a Senior Research Project (G088021N) of the FWO Vlaanderen. The research benefitted greatly from discussions at ISSI. D.L. was supported by a Senior Research Project (G088021N) of the FWO Vlaanderen. V.P. was supported by SERB start-up research grant (File No. SRG/2022/001687). R.J.M. is supported by a UKRI Future Leader Fellowship (RiPSAW—MR/T019891/1).", year = "2023", month = jul, day = "24", doi = "10.3847/2041-8213/ace423", language = "English", volume = "952", journal = "The Astrophysical Journal Letters", issn = "2041-8205", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal Letters.

Daye Lim, Tom Van Doorsselaere, David Berghmans, Richard J. Morton, Vaibhav Pant, Sudip Mandal (2023). The Role of High-frequency Transverse Oscillations in Coronal Heating . The Astrophysical Journal Letters.

Future UK solar system science @article{e3d1549965764f5f9dd625b01d0867a1, title = "Future UK solar system science", abstract = "A new Roadmap for Solar System Research in the UK has been published, and the Solar System Advisory Panel report on the processes involved in updating the previous iteration", keywords = "Geochemistry and Petrology, Geophysics, Astronomy and Astrophysics", author = "\{de Moortel\}, Ineke and Eastwood, \{Jonathan P.\} and John Bridges and Maerk Burchell and Yvonne Elseworth and Suzie Imber and Ashley King and Richard Morton", note = "Funding information: SSAP gratefully acknowledges the input and support of the entire solar system community, without which this roadmap would not have been possible. The panel is also very grateful for the support of STFC, particularly Chris Woolford, Michelle Cooper and Colin Vincent in preparing the Roadmap. For the purpose of open access, the authors have applied a Creative Commons Attribution (CC–BY) licence to any Author Accepted Manuscript version arising.", year = "2023", month = jun, day = "1", doi = "10.1093/astrogeo/atad023", language = "English", volume = "64", pages = "3.34--3.38", journal = "Astronomy and Geophysics", issn = "1366-8781", publisher = "Oxford University Press", number = "3", } . Astronomy and Geophysics.

Alfvénic waves in the inhomogeneous solar atmosphere @article{ec5a863d6c104ab5846392cfe2064ef8, title = "Alfv{\'e}nic waves in the inhomogeneous solar atmosphere", abstract = "The solar atmosphere is known to be replete with magneto-hydrodynamic wave modes, and there has been significant investment in understanding how these waves propagate through the Sun{\textquoteright}s atmosphere and deposit their energy into the plasma. The waves{\textquoteright} journey is made interesting by the vertical variation in plasma quantities that define the solar atmosphere. In addition to this large-scale inhomogeneity, a wealth of fine-scale structure through the chromosphere and corona has been brought to light by high-resolution observations over the last couple of decades. This fine-scale structure represents inhomogeneity that is thought to be perpendicular to the local magnetic fields. The implications of this form of inhomogeneity on wave propagation is still being uncovered, but is known to fundamentally change the nature of MHD wave modes. It also enables interesting physics to arise including resonances, turbulence and instabilities. Here, we review some of the key insights into how the inhomogeneity influences Alfv{\'e}nic wave propagation through the Sun{\textquoteright}s atmosphere, discussing both inhomogeneities parallel and perpendicular to the magnetic field.", keywords = "The Sun, Alfven waves, Solar corona, Solar chromosphere, Magnetohydrodynamics", author = "Richard Morton and Rahul Sharma and Edris Tajfirouzeh and Hemanthi Miriyala", note = "Funding information: The authors are supported by a UKRI Future Leader Fellowship (RiPSAW—MR/T019891/1). We also would like to thank P. Antolin for patiently discussing a number of issues, and thank I. Arregui, M. Goossens, A. Hillier, R. Soler for valuable discussions. Further thanks are to the two anonymous referees, whose insightful comments greatly improved the review. RJM would like to dedicate this review to the memory of Deenah Morton, without whose love and support this work and many others would not have been possible. For the purpose of open access, the author(s) has applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising.", year = "2023", month = mar, day = "21", doi = "10.1007/s41614-023-00118-3", language = "English", volume = "7", pages = "1--39", journal = "Reviews of Modern Plasma Physics", issn = "2367-3192", publisher = "Springer", number = "1", } . Reviews of Modern Plasma Physics.

R. J. Morton, R. Sharma, E. Tajfirouze, H. Miriyala (2023). Alfvénic waves in the inhomogeneous solar atmosphere . Reviews of Modern Plasma Physics.

Morton, R.J., Sharma, R., Tajfirouze, E., Miriyala, H.(2023). Alfvénic waves in the inhomogeneous solar atmosphere . Reviews of Modern Plasma Physics. 7. (1).

West, M.J., Seaton, D.B., Wexler, D.B., Raymond, J.C., Del Zanna, G., Rivera, Y.J., Kobelski, A.R., Chen, B., DeForest, C., Golub, L., et al.(2023). Defining the Middle Corona . Solar Physics. 298. (6).

Lim, D., Van Doorsselaere, T., Berghmans, D., Morton, R.J., Pant, V., Mandal, S.(2023). The Role of High-frequency Transverse Oscillations in Coronal Heating . Astrophysical Journal Letters. 952. (1).

De Moortel, I., Eastwood, J., Bridges, J., Burchell, M., Elsworth, Y., Imber, S., King, A., Morton, R.(2023). Future UK solar system science . Astronomy and Geophysics. 64. (3). p. 34-38.

Morton, R.J., Cunningham, R.(2023). The Fine-scale Structure of Polar Coronal Holes . Astrophysical Journal. 954. (1).

Sharma, R., Morton, R.J.(2023). Transverse energy injection scales at the base of the solar corona . Nature Astronomy. 7. (11). p. 1301-1308.

SULIS @article{6fe890c6a86c41c4ac2ac88965093ad9, title = "SULIS: A coronal magnetism explorer for ESA{\textquoteright}s Voyage 2050", abstract = "Magnetism dominates the structure and dynamics of the solar corona. To understand the true nature of the solar corona and the long-standing coronal heating problem requires measuring the vector magnetic field of the corona at a sufficiently high resolution (spatially and temporally) across a large Field-of-View (FOV). Despite the importance of the magnetic field in the physics of the corona and despite the tremendous progress made recently in the remote sensing of solar magnetic fields, reliable measurements of the coronal magnetic field strength and orientation do not exist. This is largely due to the weakness of coronal magnetic fields, previously estimated to be on the order of 1-10 G, and the difficulty associated with observing the extremely faint solar corona emission. With the Solar cUbesats for Linked Imaging Spectro-polarimetry (SULIS) mission, we plan to finally observe, in detail and over the long-term, uninterrupted measurements of the coronal magnetic vector field using a new and very affordable instrument design concept. This will be profoundly important in the study of local atmospheric coronal heating processes, as well as in measuring the nature of magnetic clouds, in particular, within geoeffective Earth-bound Coronal Mass Ejections (CMEs) for more accurate forecasting of severe space weather activity.", keywords = "Sun, Telescopes", author = "Eamon Scullion and Huw Morgan and Haosheng Lin and Viktor Fedun and Richard Morton", year = "2022", month = dec, doi = "10.1007/s10686-022-09877-2", language = "English", volume = "54", pages = "317--334", journal = "Experimental Astronomy", issn = "0922-6435", publisher = "Springer", number = "2", } . Experimental Astronomy.

Imagining the Sun: using comparative judgement to assess the impact of cross-curricular solar physics workshops @article{Davenport_2022, title={Imagining the Sun: using comparative judgement to assess the impact of cross-curricular solar physics workshops}, volume={21}, ISSN={1824-2049}, url={http://dx.doi.org/10.22323/2.21060206}, DOI={10.22323/2.21060206}, number={06}, journal={Journal of Science Communication}, publisher={Sissa Medialab Srl}, author={Davenport, Carol and Morton, Richard}, year={2022}, month=oct, pages={A06} } . Journal of Science Communication.

Imagining the Sun: using comparative judgement to assess the impact of cross-curricular solar physics workshops @article{9337eacb168c403e888fb2f003d84b62, title = "Imagining the Sun: using comparative judgement to assess the impact of cross-curricular solar physics workshops", abstract = "This paper describes a school intervention focused on visual art and solar physics using science capital and STEAM methodologies to develop STEM engagement activities. Data from 40 children (aged 8–11) in two primary schools in the North East of England are presented, using pre- and post-intervention surveys which contained free-response and likert-scale questions. The paper presents a novel, and transferable, method of evaluating children{\textquoteright}s drawings using online comparative judgement marking software, particularly suited to those without a background in qualitative research. Using comparative judgement this paper shows that the intervention led to a moderate increase in girls{\textquoteright} knowledge of solar physics.", keywords = "Visual communication, art and literature, Science and technology, Informal learning", author = "Carol Davenport and Richard Morton", year = "2022", month = oct, day = "31", doi = "10.22323/2.21060206", language = "English", volume = "21", journal = "Journal of Science Communication", issn = "1824-2049", publisher = "Scuola Internazionale Superiore di Studi Avanzati (SISSA)", number = "06", } . Journal of Science Communication.

Parallel Plasma Loops and the Energization of the Solar Corona @article{bdded3fa40f846e38785f541a9c36305, title = "Parallel Plasma Loops and the Energization of the Solar Corona", abstract = "The outer atmosphere of the Sun is composed of plasma heated to temperatures well in excess of the visible surface. We investigate short cool and warm (<1 MK) loops seen in the core of an active region to address the role of field-line braiding in energizing these structures. We report observations from the High-resolution Coronal imager (Hi-C) that have been acquired in a coordinated campaign with the Interface Region Imaging Spectrograph (IRIS). In the core of the active region, the 172 {\AA} band of Hi-C and the 1400 {\AA} channel of IRIS show plasma loops at different temperatures that run in parallel. There is a small but detectable spatial offset of less than 1'' between the loops seen in the two bands. Most importantly, we do not see observational signatures that these loops might be twisted around each other. Considering the scenario of magnetic braiding, our observations of parallel loops imply that the stresses put into the magnetic field have to relax while the braiding is applied: the magnetic field never reaches a highly braided state on these length scales comparable to the separation of the loops. This supports recent numerical 3D models of loop braiding in which the effective dissipation is sufficiently large that it keeps the magnetic field from getting highly twisted within a loop.", keywords = "360, The Sun and the Heliosphere", author = "Hardi Peter and Chitta, \{Lakshmi Pradeep\} and Feng Chen and Pontin, \{David I.\} and Winebarger, \{Amy R.\} and Leon Golub and Savage, \{Sabrina L.\} and Rachmeler, \{Laurel A.\} and Ken Kobayashi and Brooks, \{David H.\} and Cirtain, \{Jonathan W.\} and \{De Pontieu\}, Bart and McKenzie, \{David E.\} and Morton, \{Richard J.\} and Paola Testa and Tiwari, \{Sanjiv K.\} and Walsh, \{Robert W.\} and Warren, \{Harry P.\}", year = "2022", month = jul, day = "1", doi = "10.3847/1538-4357/ac7219", language = "English", volume = "933", pages = "1--20", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . The Astrophysical Journal.

Davenport, C., Morton, R.(2022). Imagining the Sun: using comparative judgement to assess the impact of cross-curricular solar physics workshops . Journal of Science Communication. 21. (6).

Peter, H., Chitta, L.P., Chen, F., Pontin, D.I., Winebarger, A.R., Golub, L., Savage, S.L., Rachmeler, L.A., Kobayashi, K., Brooks, D.H., et al.(2022). Parallel Plasma Loops and the Energization of the Solar Corona . Astrophysical Journal. 933. (2).

Scullion, E., Morgan, H., Lin, H., Fedun, V., Morton, R.(2022). SULIS: A coronal magnetism explorer for ESA’s Voyage 2050 . Experimental Astronomy. 54. (2-3). p. 317-334.

Weak damping of propagating MHD kink waves in the quiescent corona @article{b9247461812a433891346b5a268b63de, title = "Weak damping of propagating MHD kink waves in the quiescent corona", abstract = "Propagating transverse waves are thought to be a key transporter of Poynting flux throughout the Sun{\textquoteright}s atmosphere. Recent studies have shown that these transverse motions, interpreted as the magnetohydrodynamic kink mode, are prevalent throughout the corona. The associated energy estimates suggest the waves carry enough energy to meet the demands of the coronal radiative losses in the quiescent Sun. However, it is still unclear how the waves deposit their energy into the coronal plasma. We present the results from a large-scale study of propagating kink waves in the quiescent corona using data from the Coronal Multi-channel Polarimeter (CoMP). The analysis reveals that the kink waves appear to be weakly damped, which would imply low rates of energy transfer from the largescale transverse motions to smaller-scales via either uni turbulence or resonant absorption. This raises questions about how the observed kink modes would deposit their energy into the coronal plasma. Moreover, these observations, combined with the results of Monte Carlo simulations, lead us to infer that the solar corona displays a spectrum of density ratios, with a smaller density ratio (relative to the ambient corona) in quiescent coronal loops and a higher density ratio in active region coronal loops.", keywords = "Sun: corona, waves, magnetohydrodynamics (MHD)", author = "Morton, \{Richard J.\} and Tiwari, \{Ajay K.\} and \{Van Doorsselaere\}, Tom and McLaughlin, \{James A.\}", note = "Funding information: R.J.M. is supported by a UKRI Future Leader Fellowship (RiPSAW - MR/T019891/1), and thanks R. Soler and I. Arregui for providing comments on a draft of the manuscript. A.K.T is supported by the European Union{\textquoteright}s Horizon 2020 research and innovation programme under grant agreement No 824064 (ESCAPE). T.V.D. was supported by the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (grant agreement No 724326) and the C1 grant TRACEspace of Internal Funds KU Leuven. J.A.M. is supported by the Science and Technology Facilities Council (STFC) via grant number ST/T000384/1. The authors also acknowledge STFC via grant number ST/L006243/1 and for IDL support. The CoMP data is courtesy of the Mauna Loa Solar Observatory, operated by the High Altitude Observatory, as part of the National Center for Atmospheric Research (NCAR). NCAR is supported by the National Science Foundation.", year = "2021", month = dec, doi = "10.3847/1538-4357/ac324d", language = "English", volume = "923", journal = "Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . Astrophysical Journal.

Richard J. Morton, Ajay K. Tiwari, Tom Van Doorsselaere, James A. McLaughlin (2021). Weak Damping of Propagating MHD Kink Waves in the Quiescent Corona . The Astrophysical Journal.

Calculating metalation in cells reveals CobW acquires CoII for vitamin B12 biosynthesis while related proteins prefer ZnII @article{918bd236741744968991d0c592f06d68, title = "Calculating metalation in cells reveals CobW acquires CoII for vitamin B12 biosynthesis while related proteins prefer ZnII", abstract = "Protein metal-occupancy (metalation) in vivo has been elusive. To address this challenge, the available free energies of metals have recently been determined from the responses of metal sensors. Here, we use these free energy values to develop a metalation-calculator which accounts for inter-metal competition and changing metal-availabilities inside cells. We use the calculator to understand the function and mechanism of GTPase CobW, a predicted Co -chaperone for vitamin B . Upon binding nucleotide (GTP) and Mg , CobW assembles a high-affinity site that can obtain Co or Zn from the intracellular milieu. In idealised cells with sensors at the mid-points of their responses, competition within the cytosol enables Co to outcompete Zn for binding CobW. Thus, Co is the cognate metal. However, after growth in different [Co ], Co -occupancy ranges from 10 to 97\% which matches CobW-dependent B synthesis. The calculator also reveals that related GTPases with comparable Zn affinities to CobW, preferentially acquire Zn due to their relatively weaker Co affinities. The calculator is made available here for use with other proteins.", author = "Young, \{Tessa R.\} and Martini, \{Maria Alessandra\} and Foster, \{Andrew W.\} and Arthur Glasfeld and Deenah Osman and Morton, \{Richard J\} and Evelyne Deery and Warren, \{Martin J.\} and Robinson, \{Nigel J.\}", year = "2021", month = dec, day = "1", doi = "10.1038/s41467-021-21479-8", language = "English", volume = "12", journal = "Nature Communications", issn = "2041-1723", publisher = "Nature Research", number = "1", } . Nature Communications.

A Statistical Study of Propagating MHD Kink Waves in the Quiescent Corona @article{36d799a2c27b4522a310e912b6f542ee, title = "A Statistical Study of Propagating MHD Kink Waves in the Quiescent Corona", abstract = "The Coronal Multi-channel Polarimeter (CoMP) has opened up exciting opportunities to probe transverse MHD waves in the Sun{\textquoteright}s corona. The archive of CoMP data is utilized to generate a catalog of quiescent coronal loops that can be used for studying propagating kink waves. The catalog contains 120 loops observed between 2012 and 2014. This catalog is further used to undertake a statistical study of propagating kink waves in the quiet regions of the solar corona, investigating phase speeds, loop lengths, footpoint power ratio (a measure of wave power entering the corona through each footpoint of a loop) and equilibrium parameter (which provides a measure of the change in wave amplitude) values. The statistical study enables us to establish the presence of a relationship between the rate of damping and the length of the coronal loop, with longer coronal loops displaying weaker wave damping. We suggest the reason for this behavior is related to a decreasing average density contrast between the loop and ambient plasma as loop length increases. The catalog presented here will provide the community with the foundation for the further study of propagating kink waves in the quiet solar corona.", author = "Ajay Tiwari and Richard Morton and James McLaughlin", note = "Funding information: A.K.T. is supported by the European Union{\textquoteright}s Horizon 2020 research and innovation program under grant agreement No. 824064 (ESCAPE10). R.J.M. is supported by a UKRI Future Leader Fellowship (RiPSAW—MR/ T019891/1). J.A.M. is supported by the Science and Technology Facilities Council (STFC) via grant No. ST/ T000384/1. The authors acknowledge the work of the National Center for Atmospheric Research/High Altitude Observatory CoMP instrument team. The authors also acknowledge STFC via grant No. ST/L006243/1 and for IDL support.", year = "2021", month = oct, day = "1", doi = "10.3847/1538-4357/ac10c4", language = "English", volume = "919", pages = "1--10", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . The Astrophysical Journal.

Ajay K. Tiwari, Richard J. Morton, James A. McLaughlin (2021). A Statistical Study of Propagating MHD Kink Waves in the Quiescent Corona . The Astrophysical Journal.

Richard Morton, Carol Davenport, Opeyemi Dele-Ajayi, Itoro Emembolu, Annie Padwick, Antonio Portas, Jonathan Sanderson, Joe Shimwell, Jane Stonehouse, Rebecca Strachan, et al.(2021). A Theory of Change for Improving Children’s Perceptions, Aspirations and Uptake of STEM Careers . Research in Science Education. Springer Science and Business Media {LLC}

A Theory of Change for improving children's perceptions, aspirations and uptake of STEM careers @article{88a858c39181480e970dee7df67a8252, title = "A Theory of Change for improving children's perceptions, aspirations and uptake of STEM careers", abstract = "There is concern about the low numbers and diversity of young people choosing careers and study subjects in science, technology, engineering and maths (STEM) at university and beyond. Many interventions aimed at addressing this issue have focused on young people aged 14+ years old. However, these interventions have resulted in little improvement in the numbers and diversity of young people progressing into STEM careers. The aim of this study is to ask “What are the affordances of a Theory of Change (ToC) for increasing the diversity and number of young people choosing a career in STEM post-18?” An innovative ToC is introduced which provides the theoretical underpinnings and context for the complex mix of interventions necessary to lead to a significant change in the number and diversity of those choosing STEM careers. Case studies of interventions developed using the ToC are presented. This approach, and associated ToC, is widely applicable across STEM, education and public engagement fields.", keywords = "children and young people, diversity, STEM education, careers, Theory of Change, Science Capital", author = "Carol Davenport and Opeyemi Dele-Ajayi and Itoro Emembolu and Richard Morton and Annie Padwick and Antonio Portas and Jonathan Sanderson and Joe Shimwell and Jane Stonehouse and Rebecca Strachan and Leanne Wake and Gary Wells and John Woodward", note = "Funding Information: This work was supported by the Higher Education Funding Council of England (HEFCE) under a Catalyst Fund Grant (PD006) and the Reece Foundation.", year = "2021", month = aug, day = "1", doi = "10.1007/s11165-019-09909-6", language = "English", volume = "51", pages = "997–1011", journal = "Research in Science Education", issn = "0157-244X", publisher = "Springer", number = "4", } . Research in Science Education.

Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST) @article{01b8cba4648b4a7097edbb5792604392, title = "Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST)", abstract = "The National Science Foundation{\textquoteright}s Daniel K. Inouye Solar Telescope (DKIST) will revolutionize our ability to measure, understand, and model the basic physical processes that control the structure and dynamics of the Sun and its atmosphere. The first-light DKIST images, released publicly on 29 January 2020, only hint at the extraordinary capabilities that will accompany full commissioning of the five facility instruments. With this Critical Science Plan (CSP) we attempt to anticipate some of what those capabilities will enable, providing a snapshot of some of the scientific pursuits that the DKIST hopes to engage as start-of-operations nears. The work builds on the combined contributions of the DKIST Science Working Group (SWG) and CSP Community members, who generously shared their experiences, plans, knowledge, and dreams. Discussion is primarily focused on those issues to which DKIST will uniquely contribute.", keywords = "Chromosphere, Corona, Solar photosphere", author = "\{NSO, DKIST project, and DKIST instrument scientists\} and \{The DKIST Science Working Group\} and \{The DKIST Critical Science Plan Community\} and Rast, \{Mark P.\} and \{Bello Gonz{\'a}lez\}, Nazaret and \{Bellot Rubio\}, Luis and Wenda Cao and Gianna Cauzzi and Edward DeLuca and \{De Pontieu\}, Bart and Lyndsay Fletcher and Gibson, \{Sarah E.\} and Judge, \{Philip G.\} and Yukio Katsukawa and Kazachenko, \{Maria D.\} and Elena Khomenko and Enrico Landi and \{Mart{\'i}nez Pillet\}, Valent{\'i}n and Petrie, \{Gordon J.D.\} and Jiong Qiu and Rachmeler, \{Laurel A.\} and Matthias Rempel and Wolfgang Schmidt and Eamon Scullion and Xudong Sun and Welsch, \{Brian T.\} and Vincenzo Andretta and Patrick Antolin and Ayres, \{Thomas R.\} and Balasubramaniam, \{K. S.\} and Istvan Ballai and Berger, \{Thomas E.\} and Bradshaw, \{Stephen J.\} and Campbell, \{Ryan J.\} and Mats Carlsson and Roberto Casini and Rebecca Centeno and Cranmer, \{Steven R.\} and Serena Criscuoli and Craig DeForest and Yuanyong Deng and Robertus Erd{\'e}lyi and Viktor Fedun and Fischer, \{Catherine E.\} and \{Gonz{\'a}lez Manrique\}, \{Sergio J.\} and Michael Hahn and Louise Harra and Henriques, \{Vasco M.J.\} and Hurlburt, \{Neal E.\} and Sarah Jaeggli and Shahin Jafarzadeh and Rekha Jain and Wei Liu and Morton, \{Richard J.\} and Rahul Sharma", note = "Funding Information: This work rests on many years of sustained vision, effort, and dedication by DKIST and DKIST instrument, team scientists, engineers, and administrative, support personnel, the unwavering commitment of the National Science Foundation, and the support of the US taxpayers. It includes contributions from members of the DKIST Science Working Group and the DKIST Critical Science Plan Community, all of whom generously shared their experiences, plans, knowledge, and dreams. It is impossible at this stage to fully acknowledge each individual's contribution to those groups without error or error of omission, but they are all greatly appreciated. The research reported herein was based in part on the National Science Foundation's Daniel K. Inouye Solar Telescope (DKIST), a facility of the National Solar Observatory (NSO). NSO is managed by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the National Science Foundation or the Association of Universities for Research in Astronomy, Inc. DKIST is located on land of spiritual and cultural significance to Native Hawaiian people. The use of this important site to further scientific knowledge is done with great appreciation and respect. Research funded by National Science Foundation (1616538)", year = "2021", month = apr, doi = "10.1007/s11207-021-01789-2", language = "English", volume = "296", pages = "1--88", journal = "Solar Physics", issn = "0038-0938", publisher = "Springer", number = "4", } . Solar Physics.

Calculating metalation in cells reveals CobW acquires CoII for vitamin B12 biosynthesis while related proteins prefer ZnII <head> <META HTTP-EQUIV="Refresh" CONTENT="0;URL=/servlet/useragent"> </head> . Nature Communications.

R. J. Morton, K. Mooroogen, V. M. J. Henriques(2021). Transverse motions in sunspot super-penumbral fibrils . Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 379. (2190). p. 20200183. The Royal Society

S. Jafarzadeh, S. Wedemeyer, B. Fleck, M. Stangalini, D. B. Jess, R. J. Morton, M. Szydlarski, V. M. J. Henriques, X. Zhu, T. Wiegelmann, et al.(2021). An overall view of temperature oscillations in the solar chromosphere with ALMA . Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 379. (2190). p. 20200174. The Royal Society

An overall view of temperature oscillations in the solar chromosphere with ALMA @article{ae62798698eb45ea97423b1b2ab3649a, title = "An overall view of temperature oscillations in the solar chromosphere with ALMA", abstract = "By direct measurements of the gas temperature, the Atacama Large Millimeter/submillimeter Array (ALMA) has yielded a new diagnostic tool to study the solar chromosphere. Here, we present an overview of the brightness-temperature fluctuations from several high-quality and high-temporal-resolution (i.e. 1 and 2 s cadence) time series of images obtained during the first 2 years of solar observations with ALMA, in Band 3 and Band 6, centred at around 3 mm (100 GHz) and 1.25 mm (239 GHz), respectively. The various datasets represent solar regions with different levels of magnetic flux. We perform fast Fourier and Lomb-Scargle transforms to measure both the spatial structuring of dominant frequencies and the average global frequency distributions of the oscillations (i.e. averaged over the entire field of view). We find that the observed frequencies significantly vary from one dataset to another, which is discussed in terms of the solar regions captured by the observations (i.e. linked to their underlying magnetic topology). While the presence of enhanced power within the frequency range 3-5 mHz is found for the most magnetically quiescent datasets, lower frequencies dominate when there is significant influence from strong underlying magnetic field concentrations (present inside and/or in the immediate vicinity of the observed field of view). We discuss here a number of reasons which could possibly contribute to the power suppression at around 5.5 mHz in the ALMA observations. However, it remains unclear how other chromospheric diagnostics (with an exception of H line-core intensity) are unaffected by similar effects, i.e. they show very pronounced 3-min oscillations dominating the dynamics of the chromosphere, whereas only a very small fraction of all the pixels in the 10 ALMA datasets analysed here show peak power near 5.5 mHz. This article is part of the Theo Murphy meeting issue 'High-resolution wave dynamics in the lower solar atmosphere'.", keywords = "Sun: chromosphere, Sun: oscillations, Sun: radio radiation", author = "S Jafarzadeh and S Wedemeyer and B Fleck and M Stangalini and Jess, \{D B\} and Morton, \{R J\} and M Szydlarski and Henriques, \{V M J\} and X Zhu and T Wiegelmann and \{Guevara G{\'o}mez\}, \{J C\} and Grant, \{S D T\} and B Chen and K Reardon and White, \{S M\}", year = "2021", month = feb, day = "8", doi = "10.1098/rsta.2020.0174", language = "English", volume = "379", pages = "20200174", journal = "Philosophical transactions. Series A, Mathematical, physical, and engineering sciences", issn = "0962-8428", publisher = "Royal Society of London", number = "2190", } . Philosophical transactions. Series A, Mathematical, physical, and engineering sciences.

Transverse motions in sunspot super-penumbral fibrils @article{21443926ecd744969e7fe8b902f00f6a, title = "Transverse motions in sunspot super-penumbral fibrils", abstract = "Sunspots have played a key role in aiding our understanding of magnetohydrodynamic (MHD) wave phenomena in the Sun's atmosphere, and it is well known they demonstrate a number of wave phenomena associated with slow MHD modes. Recent studies have shown that transverse wave modes are present throughout the majority of the chromosphere. Using high-resolution Ca II 8542 {\AA} observations from the Swedish Solar Telescope, we provide the first demonstration that the chromospheric super-penumbral fibrils, which span out from the sunspot, also show ubiquitous transverse motions. We interpret these motions as transverse waves, in particular the MHD kink mode. We compile the statistical properties of over 2000 transverse motions to find distributions for periods and amplitudes, finding they are broadly consistent with previous observations of chromospheric transverse waves in quiet Sun fibrils. The very presence of the waves in super-penumbral fibrils raises important questions about how they are generated, and could have implications for our understanding of how MHD wave energy is transferred through the atmosphere of a sunspot. This article is part of the Theo Murphy meeting issue 'High-resolution wave dynamics in the lower solar atmosphere'.", keywords = "Sun: chromosphere, Sun: oscillations, magnetohydrodynamics (MHD), waves", author = "Morton, \{R J\} and K Mooroogen and Henriques, \{V M J\}", year = "2021", month = feb, day = "8", doi = "10.1098/rsta.2020.0183", language = "English", volume = "379", journal = "Philosophical transactions. Series A, Mathematical, physical, and engineering sciences", issn = "0962-8428", publisher = "Royal Society of London", number = "2190", } . Philosophical transactions. Series A, Mathematical, physical, and engineering sciences.

Morton, R.J., Mooroogen, K., Henriques, V.M.J.(2021). Transverse motions in sunspot super-penumbral fibrils: Waves in sunspot superpenumbral fibrils . Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 379. (2190).

Rast, M.P., Bello Gonz&#225;lez, N., Bellot Rubio, L., Cao, W., Cauzzi, G., DeLuca, E., De Pontieu, B., Fletcher, L., Gibson, S.E., Judge, P.G., et al.(2021). Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST) . Solar Physics. 296. (4).

Jafarzadeh, S., Wedemeyer, S., Fleck, B., Stangalini, M., Jess, D.B., Morton, R.J., Szydlarski, M., Henriques, V.M.J., Zhu, X., Wiegelmann, T., et al.(2021). An overall view of temperature oscillations in the solar chromosphere with ALMA: Temperature Oscillations with ALMA . Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 379. (2190).

Morton, R.J., Tiwari, A.K., Van Doorsselaere, T., McLaughlin, J.A.(2021). Weak Damping of Propagating MHD Kink Waves in the Quiescent Corona . Astrophysical Journal. 923. (2).

Young, T.R., Martini, M.A., Foster, A.W., Glasfeld, A., Osman, D., Morton, R.J., Deery, E., Warren, M.J., Robinson, N.J.(2021). Calculating metalation in cells reveals CobW acquires Co^II for vitamin B₁₂ biosynthesis while related proteins prefer Zn^II . Nature Communications. 12. (1).

Tiwari, A.K., Morton, R.J., McLaughlin, J.A.(2021). A Statistical Study of Propagating MHD Kink Waves in the Quiescent Corona . Astrophysical Journal. 919. (2).

Davenport, C., Dele-Ajayi, O., Emembolu, I., Morton, R., Padwick, A., Portas, A., Sanderson, J., Shimwell, J., Stonehouse, J., Strachan, R., et al.(2021). A Theory of Change for Improving Children’s Perceptions, Aspirations and Uptake of STEM Careers . Research in Science Education. 51. (4). p. 997-1011.

Mapping the magnetic field in the solar corona through magnetoseismology @article{22f87c2fc54a45d8ad7faacfc522dd2f, title = "Mapping the magnetic field in the solar corona through magnetoseismology", abstract = "Magnetoseismology, a technique of magnetic field diagnostics based on observations of magnetohydrodynamic (MHD) waves, has been widely used to estimate the field strengths of oscillating structures in the solar corona. However, previously magnetoseismology was mostly applied to occasionally occurring oscillation events, providing an estimate of only the average field strength or one-dimensional distribution of field strength along an oscillating structure. This restriction could be eliminated if we apply magnetoseismology to the pervasive propagating transverse MHD waves discovered with the Coronal Multi-channel Polarimeter (CoMP). Using several CoMP observations of the Fe XIII 1074.7 nm and 1079.8 nm spectral lines, we obtained maps of the plasma density and wave phase speed in the corona, which allow us to map both the strength and direction of the coronal magnetic field in the plane of sky. We also examined distributions of the electron density and magnetic field strength, and compared their variations with height in the quiet Sun and active regions. Such measurements could provide critical information to advance our understanding of the Sun{\textquoteright}s magnetism and the magnetic coupling of the whole solar atmosphere.", keywords = "solar corona, solar magnetic field, waves, magnetoseismology", author = "Zihao Yang and Hui Tian and Steven Tomczyk and Richard Morton and Xianyong Bai and Tanmoy Samanta and Yajie Chen", note = "Funding Information: This work was supported by the National Natural Science Foundation of China (Grant Nos. 11825301, 11790304(11790300)), the Strategic Priority Research Program of CAS (Grant No. XDA17040507), and Grant No. 1916321TS00103201. This material is based upon work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation under Cooperative Agreement (Grant No. 1852977). CoMP is an instrument operated by the National Center for Atmospheric Research. AIA is an instrument on SDO, a mission ofNASAs Living With a Star Program . Publisher Copyright: {\textcopyright} 2020, Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.", year = "2020", month = nov, day = "1", doi = "10.1007/s11431-020-1706-9", language = "English", volume = "63", pages = "2357--2368", journal = "Science China Technological Sciences", issn = "1674-7321", publisher = "Science Press", number = "11", } . Science China Technological Sciences.

Effect of coronal loop structure on wave heating through phase mixing @article{a486f5eacca341caab2a05fd49e2b44f, title = "Effect of coronal loop structure on wave heating through phase mixing", abstract = "Context: The mechanism(s) behind coronal heating still elude(s) direct observation and modelling of viable theoretical processes and the subsequent effect on coronal structures is one of the key tools available to assess possible heating mechanisms. Wave heating via the phase mixing of magnetohydrodynamic (MHD) transverse waves has been proposed as a possible way to convert magnetic energy into thermal energy, but MHD models increasingly suggest this is not an efficient enough mechanism. Aims: We modelled heating by phase mixing transverse MHD waves in various configurations in order to investigate whether certain circumstances can enhance the heating sufficiently to sustain the million degree solar corona and to assess the impact of the propagation and phase mixing of transverse MHD waves on the structure of the boundary shell of coronal loops. Methods: We used 3D MHD simulations of a pre-existing density enhancement in a magnetised medium and a boundary driver to trigger the propagation of transverse waves with the same power spectrum as measured by the Coronal Multi-Channel Polarimeter. We consider different density structures, boundary conditions at the non-drive footpoint, characteristics of the driver, and different forms of magnetic resistivity. Results: We find that different initial density structures significantly affect the evolution of the boundary shell and that some driver configurations can enhance the heating generated from the dissipation of the MHD waves. In particular, drivers coherent on a larger spatial scale and higher dissipation coefficients can generate significant heating, although it is still insufficient to balance the radiative losses in this setup. Conclusions: We conclude that while phase mixing of transverse MHD waves is unlikely to sustain the thermal structure of the corona, there are configurations that allow for an enhanced efficiency of this mechanism. We provide possible signatures to identify the presence of such configurations, such as the location of where the heating is deposited along the coronal loop.", keywords = "Sun: corona, Sun: oscillations, magnetohydrodynamics (MHD), Sun: atmosphere", author = "P. Pagano and \{De Moortel\}, I. and Morton, \{R. J.\}", note = "Funding Information: Acknowledgements. The authors would like to thank Tom Van Doorsselaere for the helpful discussions on uniturbulence. This work has received support from the UK Science and Technology Facilities Council (Consolidated Grant ST/K000950/1), the European Union Horizon 2020 research and innovation programme (grant agreement No. 647214) and the Research Council of Norway through its Centres of Excellence scheme, project number 262622. R. J. Morton is grateful for support from the UKRI Future Leader Fellowship (RiPSAW – MR/T019891/1) and STFC (ST/T000384/1). This work used the DiRAC@Durham facility managed by the Institute for Computational Cosmology on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk). The DiRAC@Durham equipment was funded by BEIS capital funding via STFC capital grants ST/P002293/1 and ST/R002371/1, Durham University and STFC operations grant ST/R000832/1. The DiRAC component of CSD3 was funded by BEIS capital funding via STFC capital grants ST/P002307/1 and ST/R002452/1 and STFC operations grant ST/R00689X/1. DiRAC is part of the National e-Infrastructure. We acknowledge the use of the open source (gitori-ous.org/amrvac) MPI-AMRVAC software, relying on coding efforts from C. Xia, O. Porth, R. Keppens. Publisher Copyright: {\textcopyright} ESO 2020. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.", year = "2020", month = nov, doi = "10.1051/0004-6361/202039209", language = "English", volume = "643", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", } . Astronomy & Astrophysics.

The Solar Orbiter Science Activity Plan @article{0c950b34e5b74939977449fcd1df6d93, title = "The Solar Orbiter Science Activity Plan: Translating solar and heliospheric physics questions into action", abstract = "Solar Orbiter is the first space mission observing the solar plasma both in situ and remotely, from a close distance, in and out of the ecliptic. The ultimate goal is to understand how the Sun produces and controls the heliosphere, filling the Solar System and driving the planetary environments. With six remote-sensing and four in-situ instrument suites, the coordination and planning of the operations are essential to address the following four top-level science questions: (1) What drives the solar wind and where does the coronal magnetic field originate?; (2) How do solar transients drive heliospheric variability?; (3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?; (4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? Maximising the mission's science return requires considering the characteristics of each orbit, including the relative position of the spacecraft to Earth (affecting downlink rates), trajectory events (such as gravitational assist manoeuvres), and the phase of the solar activity cycle. Furthermore, since each orbit's science telemetry will be downloaded over the course of the following orbit, science operations must be planned at mission level, rather than at the level of individual orbits. It is important to explore the way in which those science questions are translated into an actual plan of observations that fits into the mission, thus ensuring that no opportunities are missed. First, the overarching goals are broken down into specific, answerable questions along with the required observations and the so-called Science Activity Plan (SAP) is developed to achieve this. The SAP groups objectives that require similar observations into Solar Orbiter Observing Plans, resulting in a strategic, top-level view of the optimal opportunities for science observations during the mission lifetime. This allows for all four mission goals to be addressed. In this paper, we introduce Solar Orbiter's SAP through a series of examples and the strategy being followed. ", keywords = "Methods: observational, Space vehicles: instruments, Sun: general", author = "I. Zouganelis and \{De Groof\}, A. and Walsh, \{A. P.\} and Williams, \{D. R.\} and D. M{\"u}ller and \{St Cyr\}, \{O. C.\} and F. Auch{\`e}re and D. Berghmans and A. Fludra and Horbury, \{T. S.\} and Howard, \{R. A.\} and S. Krucker and M. Maksimovic and Owen, \{C. J.\} and J. Rodr{\'i}guez-Pacheco and M. Romoli and Solanki, \{S. K.\} and C. Watson and L. Sanchez and J. Lefort and P. Osuna and Gilbert, \{H. R.\} and T. Nieves-Chinchilla and L. Abbo and O. Alexandrova and A. Anastasiadis and V. Andretta and E. Antonucci and T. Appourchaux and A. Aran and Arge, \{C. N.\} and G. Aulanier and D. Baker and Bale, \{S. D.\} and M. Battaglia and \{Bellot Rubio\}, L. and A. Bemporad and M. Berthomier and K. Bocchialini and X. Bonnin and Brun, \{A. S.\} and R. Bruno and E. Buchlin and J. B{\"u}chner and R. Bucik and F. Carcaboso and R. Carr and I. Carrasco-Bl{\'a}zquez and B. Cecconi and \{Cernuda Cangas\}, I. and Chen, \{C. H.K.\} and Chitta, \{L. P.\} and T. Chust and K. Dalmasse and R. D'Amicis and \{Da Deppo\}, V. and \{De Marco\}, R. and S. Dolei and L. Dolla and \{Dudok De Wit\}, T. and \{Van Driel-Gesztelyi\}, L. and Eastwood, \{J. P.\} and \{Espinosa Lara\}, F. and L. Etesi and A. Fedorov and F. F{\'e}lix-Redondo and S. Fineschi and B. Fleck and D. Fontaine and Fox, \{N. J.\} and A. Gandorfer and V. G{\'e}not and Georgoulis, \{M. K.\} and S. Gissot and A. Giunta and L. Gizon and R. G{\'o}mez-Herrero and C. Gontikakis and G. Graham and L. Green and T. Grundy and M. Haberreiter and Harra, \{L. K.\} and Hassler, \{D. M.\} and J. Hirzberger and Ho, \{G. C.\} and G. Hurford and D. Innes and K. Issautier and James, \{A. W.\} and N. Janitzek and M. Janvier and N. Jeffrey and J. Jenkins and Y. Khotyaintsev and Klein, \{K. L.\} and Kontar, \{E. P.\} and I. Kontogiannis and C. Krafft and V. Krasnoselskikh and M. Kretzschmar and N. Labrosse and A. Lagg and F. Landini and B. Lavraud and I. Leon and Lepri, \{S. T.\} and Lewis, \{G. R.\} and P. Liewer and J. Linker and S. Livi and Long, \{D. M.\} and P. Louarn and O. Malandraki and S. Maloney and V. Martinez-Pillet and M. Martinovic and A. Masson and S. Matthews and L. Matteini and N. Meyer-Vernet and K. Moraitis and Morton, \{R. J.\} and S. Musset and G. Nicolaou and A. Nindos and H. O'Brien and \{Orozco Suarez\}, D. and M. Owens and M. Pancrazzi and A. Papaioannou and S. Parenti and E. Pariat and S. Patsourakos and D. Perrone and H. Peter and Pinto, \{R. F.\} and C. Plainaki and D. Plettemeier and Plunkett, \{S. P.\} and Raines, \{J. M.\} and N. Raouafi and H. Reid and A. Retino and L. Rezeau and P. Rochus and L. Rodriguez and L. Rodriguez-Garcia and M. Roth and Rouillard, \{A. P.\} and F. Sahraoui and C. Sasso and J. Schou and U. Sch{\"u}hle and L. Sorriso-Valvo and J. Soucek and D. Spadaro and M. Stangalini and D. Stansby and M. Steller and A. Strugarek and {\v S}tver{\'a}k and R. Susino and D. Telloni and C. Terasa and L. Teriaca and S. Toledo-Redondo and \{Del Toro Iniesta\}, \{J. C.\} and G. Tsiropoula and A. Tsounis and K. Tziotziou and F. Valentini and A. Vaivads and A. Vecchio and M. Velli and C. Verbeeck and A. Verdini and D. Verscharen and N. Vilmer and A. Vourlidas and R. Wicks and Wimmer-Schweingruber, \{R. F.\} and T. Wiegelmann and Young, \{P. R.\} and Zhukov, \{A. N.\}", year = "2020", month = oct, day = "1", doi = "10.1051/0004-6361/202038445", language = "English", volume = "642", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", } . Astronomy & Astrophysics.

Richard Morton, Zihao Yang, Christian Bethge, Hui Tian, Steven Tomczyk, Giulio Del Zanna, Scott W. McIntosh, Bidya Binay Karak, Sarah Gibson, Tanmoy Samanta, et al.(2020). Global maps of the magnetic field in the solar corona . Science. 369. (6504). p. 694--697. American Association for the Advancement of Science ({AAAS})

Global maps of the magnetic field in the solar corona @article{01efa5a04b2149c1a4c88ad2be1ae803, title = "Global maps of the magnetic field in the solar corona", abstract = "Understanding many physical processes in the solar atmosphere requires determination of the magnetic field in each atmospheric layer. However, direct measurements of the magnetic field in the Sun's corona are difficult to obtain. Using observations with the Coronal Multi-channel Polarimeter, we have determined the spatial distribution of the plasma density in the corona and the phase speed of the prevailing transverse magnetohydrodynamic waves within the plasma. We combined these measurements to map the plane-of-sky component of the global coronal magnetic field. The derived field strengths in the corona, from 1.05 to 1.35 solar radii, are mostly 1 to 4 gauss. Our results demonstrate the capability of imaging spectroscopy in coronal magnetic field diagnostics.", author = "Zihao Yang and Christian Bethge and Hui Tian and Steve Tomczyk and Richard Morton and \{Del Zanna\}, Giulio and McIntosh, \{Scott W.\} and Sarah Gibson and Tanomy Samanta and Jiansen He and Yajie Chen and Linghua Wang", note = "Funding Information: This work was supported by NSFC grants 11825301, 11790304(11790300), 41421003, 41774183, 41861134033, and 41874200; the Strategic Priority Research Program of CAS (grant no. XDA17040507), the Max Planck Partner Group program, STFC (UK) through consolidated grants to the atomic astrophysics group at DAMTP at the University of Cambridge (ST/P000665/1 and ST/T000481/1); and the Department of Science and Technology (SERB/DST) through the Ramanujan Fellowship (project no. SB/S2/RJN-017/ 2018). Publisher Copyright: {\textcopyright} 2020 American Association for the Advancement of Science. All rights reserved. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.", year = "2020", month = aug, day = "7", doi = "10.1126/science.abb4462", language = "English", volume = "369", pages = "694--697", journal = "Science", issn = "0036-8075", publisher = "American Association for the Advancement of Science", number = "6504", } . Science.

Observation and Modeling of High-temperature Solar Active Region Emission during the High-resolution Coronal Imager Flight of 2018 May 29 @article{c0075b1d3c804467b4bcc1a399544f71, title = "Observation and Modeling of High-temperature Solar Active Region Emission during the High-resolution Coronal Imager Flight of 2018 May 29", abstract = "Excellent coordinated observations of NOAA active region 12712 were obtained during the flight of the High-resolution Coronal Imager (Hi-C) sounding rocket on 2018 May 29. This region displayed a typical active region core structure with relatively short, high-temperature loops crossing the polarity inversion line and bright {"}moss{"}located at the footpoints of these loops. The differential emission measure (DEM) in the active region core is very sharply peaked at about 4 MK. Further, there is little evidence for impulsive heating events in the moss, even at the high spatial resolution and cadence of Hi-C. This suggests that active region core heating is occurring at a high frequency and keeping the loops close to equilibrium. To create a time-dependent simulation of the active region core, we combine nonlinear force-free extrapolations of the measured magnetic field with a heating rate that is dependent on the field strength and loop length and has a Poisson waiting time distribution. We use the approximate solutions to the hydrodynamic loop equations to simulate the full ensemble of active region core loops for a range of heating parameters. In all cases, we find that high-frequency heating provides the best match to the observed DEM. For selected field lines, we solve the full hydrodynamic loop equations, including radiative transfer in the chromosphere, to simulate transition region and chromospheric emission. We find that for heating scenarios consistent with the DEM, classical signatures of energy release, such as transition region brightenings and chromospheric evaporation, are weak, suggesting that they would be difficult to detect.", author = "Warren, \{Harry P.\} and Reep, \{Jeffrey W.\} and Crump, \{Nicholas A.\} and Ignacio Ugarte-Urra and Brooks, \{David H.\} and Winebarger, \{Amy R.\} and Sabrina Savage and Pontieu, \{Bart De\} and Hardi Peter and Cirtain, \{Jonathan W.\} and Leon Golub and Ken Kobayashi and David Mckenzie and Richard Morton and Laurel Rachmeler and Paola Testa and Sanjiv Tiwari and Robert Walsh", year = "2020", month = jun, day = "10", doi = "10.3847/1538-4357/ab917c", language = "English", volume = "896", journal = "Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . Astrophysical Journal.

The Drivers of Active Region Outflows into the Slow Solar Wind @article{cd98003dbc384cda82757b920a2720d2, title = "The Drivers of Active Region Outflows into the Slow Solar Wind", abstract = "Plasma outflows from the edges of active regions have been suggested as a possible source of the slow solar wind. Spectroscopic measurements show that these outflows have an enhanced elemental composition, which is a distinct signature of the slow wind. Current spectroscopic observations, however, do not have sufficient spatial resolution to distinguish what structures are being measured or determine the driver of the outflows. The High-resolution Coronal Imager (Hi-C) flew on a sounding rocket in 2018 May and observed areas of active region outflow at the highest spatial resolution ever achieved (250 km). Here we use the Hi-C data to disentangle the outflow composition signatures observed with the Hinode satellite during the flight. We show that there are two components to the outflow emission: a substantial contribution from expanded plasma that appears to have been expelled from closed loops in the active region core and a second contribution from dynamic activity in active region plage, with a composition signature that reflects solar photospheric abundances. The two competing drivers of the outflows may explain the variable composition of the slow solar wind.", author = "Brooks, \{David H.\} and Winebarger, \{Amy R.\} and Sabrina Savage and Warren, \{Harry P.\} and \{De Pontieu\}, Bart and Hardi Peter and Cirtain, \{Jonathan W.\} and Leon Golub and Ken Kobayashi and McIntosh, \{Scott W.\} and David McKenzie and Richard Morton and Laurel Rachmeler and Paola Testa and Sanjiv Tiwari and Robert Walsh", year = "2020", month = may, doi = "10.3847/1538-4357/ab8a4c", language = "English", volume = "894", pages = "1--14", journal = "Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . Astrophysical Journal.

Using Transverse Waves to Probe the Plasma Conditions at the Base of the Solar Wind @article{b101277845654ce08db4d34e15871c3d, title = "Using Transverse Waves to Probe the Plasma Conditions at the Base of the Solar Wind", abstract = "It has long been suggested that magnetohydrodynamic (MHD) waves may supply a significant proportion of the energy required to heat the corona and accelerate the solar wind. Depending on the properties of the local plasma, MHD wave modes may exhibit themselves as a variety of incompressible, transverse waves. The local magnetic field and particle density influence the properties of these waves (e.g., amplitude), thus direct measurements of transverse waves provide a mechanism to indirectly probe the local plasma conditions. We present the first statistical approach to magnetoseismology of a localized region of the solar corona, analyzing transverse waves above the south polar coronal hole on 2011 May 23. Automated methods are utilized to examine 4 hr of EUV imaging data to study how the waves evolve as a function of height (i.e., altitude) through the low corona. Between heights of 15 and 35 Mm, we find that the measured wave periods are approximately constant, and that observed displacement and velocity amplitudes increase at rates that are consistent with undamped waves. This enables us to derive a relative density profile for the coronal hole environment in question, without the use of spectroscopic data. Furthermore, our results indicate that between 5 and 15 Mm above the limb, the relative density is larger than that expected from 1D hydrostatic models, and signals a more extended transition region with a gradual change in density. This has implications for self-consistent models of wave propagation from the photosphere to the corona and beyond.", author = "Weberg, \{Micah J.\} and Morton, \{Richard J.\} and McLaughlin, \{James A.\}", year = "2020", month = may, doi = "10.3847/1538-4357/ab7c59", language = "English", volume = "894", journal = "Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . Astrophysical Journal.

Micah J. Weberg, Richard J. Morton, James A. McLaughlin (2020). Using Transverse Waves to Probe the Plasma Conditions at the Base of the Solar Wind . The Astrophysical Journal.

Is the High-Resolution Coronal Imager Resolving Coronal Strands? Results from AR 12712 @article{437369d924634bac996b282e6d39fd16, title = "Is the High-Resolution Coronal Imager Resolving Coronal Strands? Results from AR 12712", abstract = "Following the success of the first mission, the High-Resolution Coronal Imager (Hi-C) was launched for a third time (Hi-C 2.1) on 2018 May 29 from the White Sands Missile Range, NM, USA. On this occasion, 329 s of 17.2 nm data of target active region AR 12712 were captured with a cadence of ≈4 s, and a plate scale of 0.″129 pixel-1. Using data captured by Hi-C 2.1 and co-aligned observations from SDO/AIA 17.1 nm, we investigate the widths of 49 coronal strands. We search for evidence of substructure within the strands that is not detected by AIA, and further consider whether these strands are fully resolved by Hi-C 2.1. With the aid of multi-scale Gaussian normalization, strands from a region of low emission that can only be visualized against the contrast of the darker, underlying moss are studied. A comparison is made between these low-emission strands and those from regions of higher emission within the target active region. It is found that Hi-C 2.1 can resolve individual strands as small as ≈202 km, though the more typical strand widths seen are ≈513 km. For coronal strands within the region of low emission, the most likely width is significantly narrower than the high-emission strands at ≈388 km. This places the low-emission coronal strands beneath the resolving capabilities of SDO/AIA, highlighting the need for a permanent solar observatory with the resolving power of Hi-C.", author = "Thomas Williams and Walsh, \{Robert W.\} and Winebarger, \{Amy R.\} and Brooks, \{David H.\} and Cirtain, \{Jonathan W.\} and \{De Pontieu\}, Bart and Leon Golub and Ken Kobayashi and Mckenzie, \{David E.\} and Morton, \{Richard J.\} and Hardi Peter and Rachmeler, \{Laurel A.\} and Savage, \{Sabrina L.\} and Paola Testa and Tiwari, \{Sanjiv K.\} and Warren, \{Harry P.\} and Watkinson, \{Benjamin J.\}", year = "2020", month = apr, doi = "10.3847/1538-4357/ab6dcf", language = "English", volume = "892", pages = "1--13", journal = "Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . Astrophysical Journal.

Thomas Williams, Robert W. Walsh, Amy R. Winebarger, David H. Brooks, Jonathan W. Cirtain, Bart De Pontieu, Leon Golub, Ken Kobayashi, David E. McKenzie, Richard J. Morton, et al.(2020). Is the High-Resolution Coronal Imager Resolving Coronal Strands? Results from AR 12712 . The Astrophysical Journal. 892. (2). p. 134. American Astronomical Society

A chromospheric resonance cavity in a sunspot mapped with seismology @article{5bc69595a3d944c4b0a72a22c54c5148, title = "A chromospheric resonance cavity in a sunspot mapped with seismology", abstract = "Sunspots are intense collections of magnetic fields that pierce through the Sun{\textquoteright}s photosphere, with their signatures extending upwards into the outermost extremities of the solar corona. Cutting-edge observations and simulations are providing insights into the underlying wave generation, configuration and damping mechanisms found in sunspot atmospheres. However, the in situ amplification of magnetohydrodynamic waves, rising from a few hundreds of metres per second in the photosphere to several kilometres per second in the chromosphere, has, until now, proved difficult to explain. Theory predicts that the enhanced umbral wave power found at chromospheric heights may come from the existence of an acoustic resonator, which is created due to the substantial temperature gradients experienced at photospheric and transition region heights11. Here, we provide strong observational evidence of a resonance cavity existing above a highly magnetic sunspot. Through a combination of spectropolarimetric inversions and comparisons with high-resolution numerical simulations, we provide a new seismological approach to mapping the geometry of the inherent temperature stratifications across the diameter of the underlying sunspot, with the upper boundaries of the chromosphere ranging between 1,300 ± 200 km and 2,300 ± 250 km. Our findings will allow the three-dimensional structure of solar active regions to be conclusively determined from relatively commonplace two-dimensional Fourier power spectra. The techniques presented are also readily suitable for investigating temperature-dependent resonance effects in other areas of astrophysics, including the examination of Earth–ionosphere wave cavities.", keywords = "chromosphere, helioseismology, resonance cavity, sunspot", author = "Jess, \{David B.\} and Ben Snow and Houston, \{Scott J.\} and Gert Botha and Bernhard Fleck and Prasad, \{S. Krishna\} and \{Asensio Ramos\}, Andres and Richard Morton and Keys, \{Peter H.\} and Shahin Jafarzadeh and Marco Stangalini and Grant, \{Samuel D. T.\} and Christian, \{Damian J.\}", year = "2020", month = mar, day = "1", doi = "10.1038/s41550-019-0945-2", language = "English", volume = "4", pages = "220--227", journal = "Nature Astronomy", issn = "2397-3366", publisher = "Nature Publishing Group", number = "3", } . Nature Astronomy.

Williams, T., Walsh, R.W., Winebarger, A.R., Brooks, D.H., Cirtain, J.W., De Pontieu, B., Golub, L., Kobayashi, K., Mckenzie, D.E., Morton, R.J., et al.(2020). Is the High-Resolution Coronal Imager Resolving Coronal Strands? Results from AR 12712 . Astrophysical Journal. 892. (2).

Jess, D.B., Snow, B., Houston, S.J., Botha, G.J.J., Fleck, B., Krishna Prasad, S., Asensio Ramos, A., Morton, R.J., Keys, P.H., Jafarzadeh, S., et al.(2020). A chromospheric resonance cavity in a sunspot mapped with seismology . Nature Astronomy. 4. (3). p. 220-227.

Weberg, M.J., Morton, R.J., McLaughlin, J.A.(2020). Using Transverse Waves to Probe the Plasma Conditions at the Base of the Solar Wind . Astrophysical Journal. 894. (1).

Brooks, D.H., Winebarger, A.R., Savage, S., Warren, H.P., De Pontieu, B., Peter, H., Cirtain, J.W., Golub, L., Kobayashi, K., McIntosh, S.W., et al.(2020). The Drivers of Active Region Outflows into the Slow Solar Wind . Astrophysical Journal. 894. (2).

Yang, Z., Bethge, C., Tian, H., Tomczyk, S., Morton, R., Del Zanna, G., McIntosh, S.W., Karak, B.B., Gibson, S., Samanta, T., et al.(2020). Global maps of the magnetic field in the solar corona . Science. 369. (6504). p. 694-697.

Warren, H.P., Reep, J.W., Crump, N.A., Ugarte-Urra, I., Brooks, D.H., Winebarger, A.R., Savage, S., Pontieu, B.D., Peter, H., Cirtain, J.W., et al.(2020). Observation and Modeling of High-temperature Solar Active Region Emission during the High-resolution Coronal Imager Flight of 2018 May 29 . Astrophysical Journal. 896. (1).

Zouganelis, I., De Groof, A., Walsh, A.P., Williams, D.R., M&#252;ller, D., St Cyr, O.C., Auch&#232;re, F., Berghmans, D., Fludra, A., Horbury, T.S., et al.(2020). The Solar Orbiter Science Activity Plan: Translating solar and heliospheric physics questions into action . Astronomy and Astrophysics. 642.

Yang, Z.H., Tian, H., Tomczyk, S., Morton, R., Bai, X.Y., Samanta, T., Chen, Y.J.(2020). Mapping the magnetic field in the solar corona through magnetoseismology . Science China Technological Sciences. 63. (11). p. 2357-2368.

Pagano, P., De Moortel, I., Morton, R.J.(2020). Effect of coronal loop structure on wave heating through phase mixing . Astronomy and Astrophysics. 643.

The High-Resolution Coronal Imager, Flight 2.1 @article{ea94ef41183543679dbecb5dbb540be8, title = "The High-Resolution Coronal Imager, Flight 2.1", abstract = "The third flight of the High-Resolution Coronal Imager (Hi-C 2.1) occurred on May 29, 2018; the Sounding Rocket was launched from White Sands Missile Range in New Mexico. The instrument has been modified from its original configuration (Hi-C 1) to observe the solar corona in a passband that peaks near 172 {\AA}, and uses a new, custom-built low-noise camera. The instrument targeted Active Region 12712, and captured 78 images at a cadence of 4.4 s (18:56:22 – 19:01:57 UT; 5 min and 35 s observing time). The image spatial resolution varies due to quasi-periodic motion blur from the rocket; sharp images contain resolved features of at least 0.47 arcsec. There are coordinated observations from multiple ground- and space-based telescopes providing an unprecedented opportunity to observe the mass and energy coupling between the chromosphere and the corona. Details of the instrument and the data set are presented in this paper.", keywords = "Active regions, Chromosphere, active, Corona, active, Instrumentation and data management", author = "Rachmeler, \{Laurel A.\} and Winebarger, \{Amy R.\} and Savage, \{Sabrina L.\} and Leon Golub and Ken Kobayashi and Vigil, \{Genevieve D.\} and Brooks, \{David H.\} and Cirtain, \{Jonathan W.\} and \{De Pontieu\}, Bart and McKenzie, \{David E.\} and Morton, \{Richard J.\} and Hardi Peter and Paola Testa and Tiwari, \{Sanjiv K.\} and Walsh, \{Robert W.\} and Warren, \{Harry P.\} and Caroline Alexander and Darren Ansell and Beabout, \{Brent L.\} and Beabout, \{Dyana L.\} and Bethge, \{Christian W.\} and Champey, \{Patrick R.\} and Cheimets, \{Peter N.\} and Cooper, \{Mark A.\} and Creel, \{Helen K.\} and Richard Gates and Carlos Gomez and Anthony Guillory and Harlan Haight and Hogue, \{William D.\} and Todd Holloway and Richard Kenyon and Marshall, \{Joseph N.\} and McCracken, \{Jeff E.\} and Kenneth McCracken and Mitchell, \{Karen O.\} and Mark Ordway and Tim Owen and Jagan Ranganathan and Robertson, \{Bryan A.\} and Payne, \{M. Janie\} and William Podgorski and Jonathan Pryor and Jenna Samra and Sloan, \{Mark D.\} and Soohoo, \{Howard A.\} and Steele, \{D. Brandon\} and Thompson, \{Furman V.\} and Thornton, \{Gary S.\} and Benjamin Watkinson and David Windt", year = "2019", month = dec, doi = "10.1007/s11207-019-1551-2", language = "English", volume = "294", journal = "Solar Physics", issn = "0038-0938", publisher = "Springer", number = "12", } . Solar Physics.

Fine-scale Explosive Energy Release at Sites of Prospective Magnetic Flux Cancellation in the Core of the Solar Active Region Observed by Hi-C 2.1, IRIS, and SDO @article{471c83c862394785be0322706367724b, title = "Fine-scale Explosive Energy Release at Sites of Prospective Magnetic Flux Cancellation in the Core of the Solar Active Region Observed by Hi-C 2.1, IRIS, and SDO", abstract = "The second Hi-C flight (Hi-C 2.1) provided unprecedentedly high spatial and temporal resolution (∼250 km, 4.4 s) coronal EUV images of Fe ix/x emission at 172 {\AA} of AR 12712 on 2018 May 29, during 18:56:21-19:01:56 UT. Three morphologically different types (I: dot-like; II: loop-like; III: surge/jet-like) of fine-scale sudden-brightening events (tiny microflares) are seen within and at the ends of an arch filament system in the core of the AR. Although type Is (not reported before) resemble IRIS bombs (in size, and brightness with respect to surroundings), our dot-like events are apparently much hotter and shorter in span (70 s). We complement the 5 minute duration Hi-C 2.1 data with SDO/HMI magnetograms, SDO/AIA EUV images, and IRIS UV spectra and slit-jaw images to examine, at the sites of these events, brightenings and flows in the transition region and corona and evolution of magnetic flux in the photosphere. Most, if not all, of the events are seated at sites of opposite-polarity magnetic flux convergence (sometimes driven by adjacent flux emergence), implying likely flux cancellation at the microflare's polarity inversion line. In the IRIS spectra and images, we find confirming evidence of field-aligned outflow from brightenings at the ends of loops of the arch filament system. In types I and II the explosion is confined, while in type III the explosion is ejective and drives jet-like outflow. The light curves from Hi-C, AIA, and IRIS peak nearly simultaneously for many of these events, and none of the events display a systematic cooling sequence as seen in typical coronal flares, suggesting that these tiny brightening events have chromospheric/transition region origin.", author = "Tiwari, \{Sanjiv K.\} and Panesar, \{Navdeep K.\} and Moore, \{Ronald L.\} and Pontieu, \{Bart De\} and Winebarger, \{Amy R.\} and Leon Golub and Savage, \{Sabrina L.\} and Rachmeler, \{Laurel A.\} and Ken Kobayashi and Paola Testa and Warren, \{Harry P.\} and Brooks, \{David H.\} and Cirtain, \{Jonathan W.\} and McKenzie, \{David E.\} and Morton, \{Richard J.\} and Hardi Peter and Walsh, \{Robert W.\}", year = "2019", month = dec, day = "10", doi = "10.3847/1538-4357/ab54c1", language = "English", volume = "887", journal = "Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . Astrophysical Journal.

Hi-C 2.1 Observations of Jetlet-like Events at Edges of Solar Magnetic Network Lanes @article{fae8fc83ced34b5aae06c9ffe72db644, title = "Hi-C 2.1 Observations of Jetlet-like Events at Edges of Solar Magnetic Network Lanes", abstract = "We present high-resolution, high-cadence observations of six, fine-scale, on-disk jet-like events observed by the High-resolution Coronal Imager 2.1 (Hi-C 2.1) during its sounding-rocket flight. We combine the Hi-C 2.1 images with images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and the Interface Region Imaging Spectrograph (IRIS), and investigate each event's magnetic setting with co-aligned line-of-sight magnetograms from the SDO/Helioseismic and Magnetic Imager (HMI). We find that (i) all six events are jetlet-like (having apparent properties of jetlets), (ii) all six are rooted at edges of magnetic network lanes, (iii) four of the jetlet-like events stem from sites of flux cancelation between majority-polarity network flux and merging minority-polarity flux, and (iv) four of the jetlet-like events show brightenings at their bases reminiscent of the base brightenings in coronal jets. The average spire length of the six jetlet-like events (9000 ± 3000 km) is three times shorter than that for IRIS jetlets (27,000 ± 8000 km). While not ruling out other generation mechanisms, the observations suggest that at least four of these events may be miniature versions of both larger-scale coronal jets that are driven by minifilament eruptions and still-larger-scale solar eruptions that are driven by filament eruptions. Therefore, we propose that our Hi-C events are driven by the eruption of a tiny sheared-field flux rope, and that the flux rope field is built and triggered to erupt by flux cancelation.", author = "Panesar, \{Navdeep K.\} and Sterling, \{Alphonse C.\} and Moore, \{Ronald L.\} and Winebarger, \{Amy R.\} and Tiwari, \{Sanjiv K.\} and Savage, \{Sabrina L.\} and Golub, \{Leon E.\} and Rachmeler, \{Laurel A.\} and Ken Kobayashi and Brooks, \{David H.\} and Cirtain, \{Jonathan W.\} and Pontieu, \{Bart De\} and McKenzie, \{David E.\} and Morton, \{Richard J.\} and Hardi Peter and Paola Testa and Walsh, \{Robert W.\} and Warren, \{Harry P.\}", year = "2019", month = dec, day = "10", doi = "10.3847/2041-8213/ab594a", language = "English", volume = "887", journal = "Astrophysical Journal Letters", issn = "2041-8205", publisher = "American Astronomical Society", number = "1", } . Astrophysical Journal Letters.

David B. Jess, Ben Snow, Scott J. Houston, Gert J. J. Botha, Bernhard Fleck, S. Krishna Prasad, Andr&#233;s Asensio Ramos, Richard J. Morton, Peter H. Keys, Shahin Jafarzadeh, et al. (2019). A chromospheric resonance cavity in a sunspot mapped with seismology . Nature Astronomy.

Vaibhav Pant, Norbert Magyar, Tom Van Doorsselaere, Richard J. Morton (2019). Investigating “Dark” Energy in the Solar Corona Using Forward Modeling of MHD Waves . The Astrophysical Journal.

Investigating “Dark” Energy in the Solar Corona Using Forward Modeling of MHD Waves @article{4edd89b6bdaf4fe6b4b14195948a5c85, title = "Investigating “Dark” Energy in the Solar Corona Using Forward Modeling of MHD Waves", abstract = "It is now well established that Alfv{\'e}nic waves are ubiquitous in the solar corona. However, the Alfv{\'e}nic wave energy estimated from Doppler velocity measurements in the corona was found to be four orders of magnitude less than that estimated from nonthermal line widths. McIntosh \& De Pontieu suggested that this discrepancy in energy might be due to the line-of-sight (LOS) superposition of several oscillating structures, which can lead to an underestimation of the Alfv{\'e}nic wave amplitudes and energies. McIntosh \& De Pontieu termed this coronal {"}dark{"} or {"}hidden{"} energy. However, their simulations required the use of an additional, unknown source of Alfv{\'e}nic wave energy to obtain agreement with measurements of the coronal nonthermal line widths. In this study, we investigate the requirement of this unknown source of additional {"}dark{"} energy in the solar corona using gravitationally stratified 3D magnetohydrodynamic (MHD) simulations of propagating waves. We excite the transverse MHD waves and generate synthetic observations of the Fe xiii emission line. We establish that LOS superposition greatly reduces the Doppler velocity amplitudes and increases the nonthermal line widths. Importantly, our model generates the observed wedge-shape correlation between Doppler velocities and nonthermal line widths. We find that the observed wave energy is only 0.2\%–1\% of the true wave energy, which explains the 2–3 order-of-magnitude energy discrepancy. We conclusively establish that true wave energies are hidden in nonthermal line widths. Hence, our results rule out the requirement for an additional {"}dark{"} energy in the solar corona.", author = "Vaibhav Pant and Norbert Magyar and \{Van Doorsselaere\}, Tom and Richard Morton", year = "2019", month = aug, day = "20", doi = "10.3847/1538-4357/ab2da3", language = "English", volume = "881", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . The Astrophysical Journal.

Damping of Propagating Kink Waves in the Solar Corona @article{121ccf71c6fe48f8ac990c8972835392, title = "Damping of Propagating Kink Waves in the Solar Corona", abstract = "Alfv{\'e}nic waves have gained renewed interest since the existence of ubiquitous propagating kink waves were discovered in the corona. It has long been suggested that Alfv{\'e}nic waves play an important role in coronal heating and the acceleration of the solar wind. To this effect, it is imperative to understand the mechanisms that enable their energy to be transferred to the plasma. Mode conversion via resonant absorption is believed to be one of the main mechanisms for kink wave damping and it is considered to play a key role in the process of energy transfer. This study examines the damping of propagating kink waves in quiescent coronal loops using the Coronal Multi-channel Polarimeter. A coherence-based method is used to track the Doppler velocity signal of the waves, which enables us to investigate the spatial evolution of velocity perturbations. The power ratio of outward to inward propagating waves is used to estimate the associated damping lengths and quality factors. To enable accurate estimates of these quantities, we provide the first derivation of a likelihood function suitable for fitting models to the ratio of two power spectra obtained from discrete Fourier transforms. Maximum likelihood estimation is used to fit an exponential damping model to the observed variation in power ratio as a function of frequency. We confirm earlier indications that propagating kink waves are undergoing frequency-dependent damping. Additionally, we find that the rate of damping decreases, or equivalently the damping length increases, for longer coronal loops that reach higher in the corona.", keywords = "Sun: corona, Sun: oscillations, Sun: magnetic fields", author = "Ajay Tiwari and Richard Morton and Stephane Regnier and James McLaughlin", year = "2019", month = may, day = "10", doi = "10.3847/1538-4357/ab164b", language = "English", volume = "876", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . The Astrophysical Journal.

Ajay K. Tiwari, Richard J. Morton, St&#233;phane R&#233;gnier, James A. McLaughlin(2019). Damping of Propagating Kink Waves in the Solar Corona . The Astrophysical Journal. 876. (2). p. 106. American Astronomical Society

Deenah Osman, Maria Alessandra Martini, Andrew W. Foster, Junjun Chen, Andrew J. P. Scott, Richard J. Morton, Jonathan W. Steed, Elena Lurie-Luke, Thomas G. Huggins, Andrew D. Lawrence, et al.(2019). Bacterial sensors define intracellular free energies for correct enzyme metalation . Nature Chemical Biology. 15. (3). p. 241--249. Springer Science and Business Media {LLC}

Bacterial sensors define intracellular free energies for correct enzyme metalation @article{1be41073ad734ebb981dcedd4abe23a4, title = "Bacterial sensors define intracellular free energies for correct enzyme metalation", abstract = " There is a challenge for metalloenzymes to acquire their correct metals because some inorganic elements form more stable complexes with proteins than do others. These preferences can be overcome provided some metals are more available than others. However, while the total amount of cellular metal can be readily measured, the available levels of each metal have been more difficult to define. Metal-sensing transcriptional regulators are tuned to the intracellular availabilities of their cognate ions. Here we have determined the standard free energy for metal complex formation to which each sensor, in a set of bacterial metal sensors, is attuned: the less competitive the metal, the less favorable the free energy and hence the greater availability to which the cognate allosteric mechanism is tuned. Comparing these free energies with values derived from the metal affinities of a metalloprotein reveals the mechanism of correct metalation exemplified here by a cobalt chelatase for vitamin B12. ", author = "Deenah Osman and Martini, \{Maria Alessandra\} and Foster, \{Andrew W.\} and Junjun Chen and Scott, \{Andrew J.P.\} and Morton, \{Richard J.\} and Steed, \{Jonathan W.\} and Elena Lurie-Luke and Huggins, \{Thomas G.\} and Lawrence, \{Andrew D.\} and Evelyne Deery and Warren, \{Martin J.\} and Chivers, \{Peter T.\} and Robinson, \{Nigel J.\}", year = "2019", month = mar, day = "1", doi = "10.1038/s41589-018-0211-4", language = "English", volume = "15", pages = "241--249", journal = "Nature Chemical Biology", issn = "1552-4450", publisher = "Nature Research", number = "3", } . Nature Chemical Biology.

A basal contribution from p-modes to the Alfvénic wave flux in the Sun’s corona @article{cc795e4406b44576bf43e82257d9f1f3, title = "A basal contribution from p-modes to the Alfv{\'e}nic wave flux in the Sun{\textquoteright}s corona", abstract = "Many cool stars possess complex magnetic fields 1 that are considered to undertake a central role in the structuring and energizing of their atmospheres 2 . Alfv{\'e}nic waves are thought to make a critical contribution to energy transfer along these magnetic fields, with the potential to heat plasma and accelerate stellar winds 3–5 . Despite Alfv{\'e}nic waves having been identified in the Sun{\textquoteright}s atmosphere, the nature of the basal wave energy flux is poorly understood. It is generally assumed that the associated Poynting flux is generated solely in the photosphere and propagates into the corona, typically through the continuous buffeting of magnetic fields by turbulent convective cells 4,6,7 . Here, we provide evidence that the Sun{\textquoteright}s internal acoustic modes also contribute to the basal flux of Alfv{\'e}nic waves, delivering a spatially ubiquitous input to the coronal energy balance that is sustained over the solar cycle. Alfv{\'e}nic waves are thus a fundamental feature of the Sun{\textquoteright}s corona. Acknowledging that internal acoustic modes have a key role in injecting additional Poynting flux into the upper atmospheres of Sun-like stars has potentially significant consequences for the modelling of stellar coronae and winds. ", author = "Richard Morton and Micah Weberg and James McLaughlin", year = "2019", month = mar, day = "1", doi = "10.1038/s41550-018-0668-9", language = "English", volume = "3", pages = "223--229", journal = "Nature Astronomy", issn = "2397-3366", publisher = "Nature Publishing Group", number = "3", } . Nature Astronomy.

R. J. Morton, M. J. Weberg, J. A. McLaughlin (2019). A basal contribution from p-modes to the Alfvénic wave flux in the Sun’s corona . Nature Astronomy.

Morton, R.J., Weberg, M.J., McLaughlin, J.A.(2019). A basal contribution from p-modes to the Alfvénic wave flux in the Sun’s corona . Nature Astronomy. 3. (3). p. 223-229.

Tiwari, A.K., Morton, R.J., R&#233;gnier, S., McLaughlin, J.A.(2019). Damping of Propagating Kink Waves in the Solar Corona . Astrophysical Journal. 876. (2).

Pant, V., Magyar, N., Van Doorsselaere, T., Morton, R.J.(2019). Investigating "dark" Energy in the Solar Corona Using Forward Modeling of MHD Waves . Astrophysical Journal. 881. (2).

Panesar, N.K., Sterling, A.C., Moore, R.L., Winebarger, A.R., Tiwari, S.K., Savage, S.L., Golub, L.E., Rachmeler, L.A., Kobayashi, K., Brooks, D.H., et al.(2019). Hi-C 2.1 Observations of Jetlet-like Events at Edges of Solar Magnetic Network Lanes . Astrophysical Journal Letters. 887. (1).

Rachmeler, L.A., Winebarger, A.R., Savage, S.L., Golub, L., Kobayashi, K., Vigil, G.D., Brooks, D.H., Cirtain, J.W., De Pontieu, B., McKenzie, D.E., et al.(2019). The High-Resolution Coronal Imager, Flight 2.1 . Solar Physics. 294. (12).

Tiwari, S.K., Panesar, N.K., Moore, R.L., Pontieu, B.D., Winebarger, A.R., Golub, L., Savage, S.L., Rachmeler, L.A., Kobayashi, K., Testa, P., et al.(2019). Fine-scale Explosive Energy Release at Sites of Prospective Magnetic Flux Cancellation in the Core of the Solar Active Region Observed by Hi-C 2.1, IRIS, and SDO . Astrophysical Journal. 887. (1).

Osman, D., Martini, M.A., Foster, A.W., Chen, J., Scott, A.J.P., Morton, R.J., Steed, J.W., Lurie-Luke, E., Huggins, T.G., Lawrence, A.D., et al.(2019). Bacterial sensors define intracellular free energies for correct enzyme metalation . Nature Chemical Biology. 15. (3). p. 241-249.

Photospheric Observations of Surface and Body Modes in Solar Magnetic Pores @article{7d0d76715f8742329e7f0f4ddfee323b, title = "Photospheric Observations of Surface and Body Modes in Solar Magnetic Pores", abstract = "Over the past number of years, great strides have been made in identifying the various low-order magnetohydrodynamic wave modes observable in a number of magnetic structures found within the solar atmosphere. However, one aspect of these modes that has remained elusive, until now, is their designation as either surface or body modes. This property has significant implications for how these modes transfer energy from the waveguide to the surrounding plasma. Here, for the first time to our knowledge, we present conclusive, direct evidence of these wave characteristics in numerous pores that were observed to support sausage modes. As well as outlining methods to detect these modes in observations, we make estimates of the energies associated with each mode. We find surface modes more frequently in the data, as well as that surface modes appear to carry more energy than those displaying signatures of body modes. We find frequencies in the range of ∼2-12 mHz, with body modes as high as 11 mHz, but we do not find surface modes above 10 mHz. It is expected that the techniques we have applied will help researchers search for surface and body signatures in other modes and in differing structures from those presented here.", keywords = "magnetic fields, magnetohydrodynamics (MHD), Sun: activity, Sun: evolution, Sun: oscillations, Sun: photosphere", author = "Keys, \{Peter H.\} and Morton, \{Richard J.\} and Jess, \{David B.\} and Gary Verth and Grant, \{Samuel D.T.\} and Mihalis Mathioudakis and Mackay, \{Duncan H.\} and Doyle, \{John G.\} and Christian, \{Damian J.\} and Keenan, \{Francis P.\} and Robertus Erd{\'e}lyi", year = "2018", month = apr, day = "10", doi = "10.3847/1538-4357/aab432", language = "English", volume = "857", journal = "Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . Astrophysical Journal.

Peter H. Keys, Richard J. Morton, David B. Jess, Gary Verth, Samuel D. T. Grant, Mihalis Mathioudakis, Duncan H. Mackay, John G. Doyle, Damian J. Christian, Francis P. Keenan, et al. (2018). Photospheric Observations of Surface and Body Modes in Solar Magnetic Pores . The Astrophysical Journal.

Keys, Peter H., Morton, Richard J., Jess, David B., Verth, Gary, Grant, Samuel D. T., Mathioudakis, Mihalis, Mackay, Duncan H., Doyle, John G., Christian, Damian J., Keenan, Francis P., et al. (2018). Photospheric observations of surface and body modes in solar magnetic pores .

An Automated Algorithm for Identifying and Tracking Transverse Waves in Solar Images @article{823ec7b43d1248b4ad1366b50e490e88, title = "An Automated Algorithm for Identifying and Tracking Transverse Waves in Solar Images", abstract = "Recent instrumentation has demonstrated that the solar atmosphere supports omnipresent transverse waves, which could play a key role in energizing the solar corona. Large-scale studies are required in order to build up an understanding of the general properties of these transverse waves. To help facilitate this, we present an automated algorithm for identifying and tracking features in solar images and extracting the wave properties of any observed transverse oscillations. We test and calibrate our algorithm using a set of synthetic data, which includes noise and rotational effects. The results indicate an accuracy of 1\%-2\% for displacement amplitudes and 4\%-10\% for wave periods and velocity amplitudes. We also apply the algorithm to data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and find good agreement with previous studies. Of note, we find that 35\%-41\% of the observed plumes exhibit multiple wave signatures, which indicates either the superposition of waves or multiple independent wave packets observed at different times within a single structure. The automated methods described in this paper represent a significant improvement on the speed and quality of direct measurements of transverse waves within the solar atmosphere. This algorithm unlocks a wide range of statistical studies that were previously impractical.", keywords = "methods: data analysis, Sun: corona, Sun: oscillations, Sun: UV radiation, waves", author = "Micah Weberg and Richard Morton and James McLaughlin", year = "2018", month = jan, day = "5", doi = "10.3847/1538-4357/aa9e4a", language = "English", volume = "852", journal = "The Astrophysical Journal", issn = "1538-4357", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

Micah J. Weberg, Richard J. Morton, James A. McLaughlin (2018). An Automated Algorithm for Identifying and Tracking Transverse Waves in Solar Images . The Astrophysical Journal.

Weberg, M.J., Morton, R.J., McLaughlin, J.A.(2018). An Automated Algorithm for Identifying and Tracking Transverse Waves in Solar Images . Astrophysical Journal. 852. (1).

Keys, P.H., Morton, R.J., Jess, D.B., Verth, G., Grant, S.D.T., Mathioudakis, M., Mackay, D.H., Doyle, J.G., Christian, D.J., Keenan, F.P., et al.(2018). Photospheric Observations of Surface and Body Modes in Solar Magnetic Pores . Astrophysical Journal. 857. (1).

Weberg, M. J., Morton, R. J., McLaughlin, J. A. (2017). Annual Properties of Transverse Waves in the Corona over most of Solar Cycle 24 .

Dynamics of internetwork chromospheric fibrils: Basic properties and magnetohydrodynamic kink waves @article{14ece98216004b5bbb05581673d31056, title = "Dynamics of internetwork chromospheric fibrils: Basic properties and magnetohydrodynamic kink waves", abstract = "Aims. Current observational instruments are now providing data with the necessary temporal and spatial cadences required to examine highly dynamic, fine-scale magnetic structures in the solar atmosphere. Using the spectroscopic imaging capabilities of the Swedish Solar Telescope, we aim to provide the first investigation on the nature and dynamics of elongated absorption features (fibrils) observed in Hα in the internetwork. Methods. We observe and identify a number of internetwork fibrils, which form away from the kilogauss, network magnetic flux, and we provide a synoptic view on their behaviour. The internetwork fibrils are found to support wave-like behaviour, which we interpret as magnetohydrodynamic (MHD) kink waves. The properties of these waves, that is, amplitude, period, and propagation speed, are measured from time-distance diagrams and we attempt to exploit them via magneto-seismology in order to probe the variation of plasma properties along the wave-guides. Results. We found that the Internetwork (IN) fibrils appear, disappear, and re-appear on timescales of tens of minutes, suggesting that they are subject to repeated heating. No clear photospheric footpoints for the fibrils are found in photospheric magnetograms or Hα wing images. However, we suggest that they are magnetised features as the majority of them show evidence of supporting propagating MHD kink waves, with a modal period of 120 s. Additionally, one IN fibril is seen to support a flow directed along its elongated axis, suggesting a guiding field. The wave motions are found to propagate at speeds significantly greater than estimates for typical chromospheric sound speeds. Through their interpretation as kink waves, the measured speeds provide an estimate for local average Alfv{\'e}n speeds. Furthermore, the amplitudes of the waves are also found to vary as a function of distance along the fibrils, which can be interpreted as evidence of stratification of the plasma in the neighbourhood of the IN fibril.", keywords = "Sun: chromosphere, Sun: oscillations, Magnetohydrodynamics (MHD), Waves", author = "Krishna Mooroogen and Richard Morton and Vasco Henriques", year = "2017", month = nov, day = "9", doi = "10.1051/0004-6361/201730926", language = "English", volume = "607", journal = "Astronomy and Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", } . Astronomy and Astrophysics.

Long, D. M., Valori, G., P&#233;rez-Su&#225;rez, D., Morton, R. J., V&#225;squez, A. M. (2017). Measuring the magnetic field of a trans-equatorial loop system using coronal seismology (Corrigendum) .

K. Mooroogen, R. J. Morton, V. Henriques(2017). Dynamics of internetwork chromospheric fibrils: Basic properties and magnetohydrodynamic kink waves . Astronomy & Astrophysics. 607. p. A46. {EDP} Sciences

S. Krishna Prasad, D. B. Jess, T. Van Doorsselaere, G. Verth, R. J. Morton, V. Fedun, R. Erd&#233;lyi, D. J. Christian (2017). The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere . The Astrophysical Journal.

The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere @article{42b767d9cf054b47942ea5fe42f6f8c6, title = "The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere", abstract = "High spatial and temporal resolution images of a sunspot, obtained simultaneously in multiple optical and UV wavelengths, are employed to study the propagation and damping characteristics of slow magnetoacoustic waves up to transition region heights. Power spectra are generated from intensity oscillations in sunspot umbra, across multiple atmospheric heights, for frequencies up to a few hundred mHz. It is observed that the power spectra display a power-law dependence over the entire frequency range, with a significant enhancement around 5.5 mHz found for the chromospheric channels. The phase difference spectra reveal a cutoff frequency near 3 mHz, up to which the oscillations are evanescent, while those with higher frequencies propagate upward. The power-law index appears to increase with atmospheric height. Also, shorter damping lengths are observed for oscillations with higher frequencies suggesting frequency-dependent damping. Using the relative amplitudes of the 5.5 mHz (3 minute) oscillations, we estimate the energy flux at different heights, which seems to decay gradually from the photosphere, in agreement with recent numerical simulations. Furthermore, a comparison of power spectra across the umbral radius highlights an enhancement of high-frequency waves near the umbral center, which does not seem to be related to magnetic field inclination angle effects.", author = "Prasad, \{Samayamanthula Krishna\} and David Jess and Doorsselaere, \{T. Van\} and G. Verth and Morton, \{R. J.\} and V. Fedun and R. Erd{\'e}lyi and Damian Christian", year = "2017", month = sep, day = "14", doi = "10.3847/1538-4357/aa86b5", language = "English", volume = "847", pages = "5", journal = "The Astrophysical Journal", issn = "2041-8205", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

Krishna Prasad, S., Jess, D. B., Van Doorsselaere, T., Verth, G., Morton, R. J., Fedun, V., Erdelyi, R., Christian, D. J. (2017). The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere .

Mooroogen, K., Morton, R. J., Henriques, V. (2017). Dynamics of internetwork chromospheric fibrils: Basic properties and MHD kink waves .

Measuring the magnetic field of a trans-equatorial loop system using coronal seismology @article{e02606656cd944f88efee25c21456de7, title = "Measuring the magnetic field of a trans-equatorial loop system using coronal seismology", abstract = "Context - EIT waves are freely-propagating global pulses in the low corona which are strongly associated with the initial evolution of coronal mass ejections (CMEs). They are thought to be large-amplitude, fast-mode magnetohydrodynamic waves initially driven by the rapid expansion of a CME in the low corona. Aims - An EIT wave was observed on 6 July 2012 to impact an adjacent trans-equatorial loop system which then exhibited a decaying oscillation as it returned to rest. Observations of the loop oscillations were used to estimate the magnetic field strength of the loop system by studying the decaying oscillation of the loop, measuring the propagation of ubiquitous transverse waves in the loop and extrapolating the magnetic field from observed magnetograms. Methods - Observations from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory (SDO/AIA) and the Coronal Multi-channel Polarimeter (CoMP) were used to study the event. An Empirical Mode Decomposition analysis was used to characterise the oscillation of the loop system in CoMP Doppler velocity and line width and in AIA intensity. Results - The loop system was shown to oscillate in the 2nd harmonic mode rather than at the fundamental frequency, with the seismological analysis returning an estimated magnetic field strength of ≈ 5.5 ± 1.5 G. This compares to the magnetic field strength estimates of ≈1–9 G and ≈3–9 G found using the measurements of transverse wave propagation and magnetic field extrapolation respectively.", keywords = "Sun: corona, Sun: magnetic fields, Sun: oscillations", author = "Long, \{David M.\} and Gherardo Valori and David P{\'e}rez-Su{\'a}rez and Richard Morton and Alberto V{\'a}squez", year = "2017", month = jul, day = "19", doi = "10.1051/0004-6361/201730413", language = "English", volume = "603", pages = "A101", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", } . Astronomy & Astrophysics.

D. M. Long, G. Valori, D. P&#233;rez-Su&#225;rez, R. J. Morton, A. M. V&#225;squez(2017). Measuring the magnetic field of a trans-equatorial loop system using coronal seismology . Astronomy & Astrophysics. {EDP} Sciences

B. Snow, G. J. J. Botha, S. R&#233;gnier, R. J. Morton, E. Verwichte, P. R. Young (2017). Observational Signatures of a Kink-unstable Coronal Flux Rope Using Hinode/EIS . The Astrophysical Journal.

Observational signatures of a kink-unstable coronal flux rope using Hinode/EIS @article{d2c1378ea87a4e7896931c250fa13c5b, title = "Observational signatures of a kink-unstable coronal flux rope using Hinode/EIS", abstract = "The signatures of energy release and energy transport for a kink-unstable coronal flux rope are investigated via forward modelling. Synthetic intensity and Doppler maps are generated from a 3D numerical simulation. The CHIANTI database is used to compute intensities for three Hinode/EIS emission lines that cover the thermal range of the loop. The intensities and Doppler velocities at simulation resolution are spatially degraded to the Hinode/EIS pixel size (1′′), convolved using a Gaussian point-spread function (3′′), and exposed for a characteristic time of 50 seconds. The synthetic images generated for rasters (moving slit) and sit-and-stare stationary slit) are analysed to find the signatures of the twisted flux and the associated instability. We find that there are several qualities of a kink-unstable coronal flux rope that can be detected observationally using Hinode/EIS, namely the growth of the loop radius, the increase in intensity towards the radial edge of the loop, and the Doppler velocity following an internal twisted magnetic field line. However, EIS cannot resolve the small, transient features present in the simulation, such as sites of small-scale reconnection (e.g. nanoflares).", keywords = "magnetic reconnection, magnetohydrodynamics (MHD), Sun: corona, Sun: magnetic fields, Sun: UV radiation", author = "Ben Snow and Gert Botha and Stephane Regnier and Richard Morton and Erwin Verwichte and Young, \{Peter R.\}", year = "2017", month = jun, day = "8", doi = "10.3847/1538-4357/aa6d0e", language = "English", volume = "842", pages = "16", journal = "The Astrophysical Journal", issn = "2041-8205", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

Project SunbYte: solar astronomy on a budget @article{845a88e427884a7186d76e0d231c2b5b, title = "Project SunbYte: solar astronomy on a budget", author = "Richard Cook and James McLaughlin and Richard Morton and Eamon Scullion and Sergiy Shelyag and Alexander Hamilton and Sergei Zharkov and Dave Jess and Mark Wrigley", note = "This article has been accepted for publication in Astronomy \& Geophysics {\textcopyright}: 2017 Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.", year = "2017", month = apr, day = "1", doi = "10.1093/astrogeo/atx058", language = "English", volume = "58", pages = "2.24--2.25", journal = "Astronomy \& Geophysics", issn = "1366-8781", publisher = "Oxford University Press", number = "2", } . Astronomy & Geophysics.

Alvarez Gonzalez, F., Badilita, A. -M., Baker, A., Cho, Y. -H., Dhot, N., Fedun, V., Hare, C., He, T., Hobbs, M., Javed, M., et al. (2017). Project SunbYte: solar astronomy on a budget .

Long, David M., Valori, Gherardo, P&#233;rez-Su&#225;rez, David, Morton, Richard J., Marcos V&#225;squez, Alberto (2017). Measuring the magnetic field of a trans-equatorial loop system using coronal seismology .

Gonzalez, F.A., Badilita, A.-M., Baker, A., Cho, Y.-H., Dhot, N., Fedun, V., Hare, C., He, T., Hobbs, M., Javed, M., et al.(2017). Project SunbYte: Solar astronomy on a budget . Astronomy and Geophysics. 58. (2). p. 2.24-2.25.

Long, D.M., Valori, G., P&#233;rez-Su&#225;rez, D., Morton, R.J., V&#225;squez, A.M.(2017). Measuring the magnetic field of a trans-equatorial loop system using coronal seismology . Astronomy and Astrophysics. 603.

Prasad, S.K., Jess, D.B., Doorsselaere, T.V., Verth, G., Morton, R.J., Fedun, V., Erd&#233;lyi, R., Christian, D.J.(2017). The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere . Astrophysical Journal. 847. (1).

Mooroogen, K., Morton, R.J., Henriques, V.(2017). Dynamics of internetwork chromospheric fibrils: Basic properties and magnetohydrodynamic kink waves . Astronomy and Astrophysics. 607.

Snow, B., Botha, G.J.J., R&#233;gnier, S., Morton, R.J., Verwichte, E., Young, P.R.(2017). Observational Signatures of a Kink-unstable Coronal Flux Rope Using Hinode/EIS . Astrophysical Journal. 842. (1).

Morton, R. J., Scullion, E., Bloomfield, D. S., McLaughlin, J. A., Regnier, S., McIntosh, S. W., Tomczyk, S., Young, P. (2016). Exploring Coronal Dynamics: A Next Generation Solar Physics Mission white paper .

Model fitting of kink waves in the solar atmosphere: Gaussian damping and time-dependence @article{9567b816c0e9476097cb06e6b7b796ab, title = "Model fitting of kink waves in the solar atmosphere: Gaussian damping and time-dependence", abstract = "Aims. Observations of the solar atmosphere have shown that magnetohydrodynamic waves are ubiquitous throughout. Improvements in instrumentation and the techniques used for measurement of the waves now enables subtleties of competing theoretical models to be compared with the observed waves behaviour. Some studies have already begun to undertake this process. However, the techniques employed for model comparison have generally been unsuitable and can lead to erroneous conclusions about the best model. The aim here is to introduce some robust statistical techniques for model comparison to the solar waves community, drawing on the experiences from other areas of astrophysics. In the process, we also aim to investigate the physics of coronal loop oscillations. Methods. The methodology exploits least-squares fitting to compare models to observational data. We demonstrate that the residuals between the model and observations contain significant information about the ability for the model to describe the observations, and show how they can be assessed using various statistical tests. In particular we discuss the Kolmogorov-Smirnoff one and two sample tests, as well as the runs test. We also highlight the importance of including any observational trend line in the model-fitting process. Results. To demonstrate the methodology, an observation of an oscillating coronal loop undergoing standing kink motion is used. The model comparison techniques provide evidence that a Gaussian damping profile provides a better description of the observed wave attenuation than the often used exponential profile. This supports previous analysis from Pascoe et al. (2016). Further, we use the model comparison to provide evidence of time-dependent wave properties of a kink oscillation, attributing the behaviour to the thermodynamic evolution of the local plasma.", keywords = "Sun: corona / waves / magnetohydrodynamics (MHD) / Sun: oscillations", author = "Richard Morton and Krishna Mooroogen", year = "2016", month = sep, doi = "10.1051/0004-6361/201628613", language = "English", volume = "593", pages = "A59", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", } . Astronomy & Astrophysics.

R. J. Morton, S. Tomczyk, R. F. Pinto (2016). A GLOBAL VIEW OF VELOCITY FLUCTUATIONS IN THE CORONA BELOW 1.3 R⊙ WITH CoMP . The Astrophysical Journal.

A global view of velocity fluctuations in the corona below 1.3r⊙ with comp @article{b371e04f0e9c4c6dbebfbb3903f69749, title = "A global view of velocity fluctuations in the corona below 1.3r⊙ with comp", abstract = "The Coronal Multi-channel Polarimeter (CoMP) has previously demonstrated the presence of Doppler velocity fluctuations in the solar corona. The observed fluctuations are thought to be transverse waves, i.e., highly incompressible motions whose restoring force is dominated by the magnetic tension, some of which demonstrate clear periodicity. We aim to exploit CoMP{\textquoteright}s ability to provide high cadence observations of the off-limb corona to investigate the properties of velocity fluctuations in a range of coronal features, providing insight into how (whether) the properties of the waves are influenced by the varying magnetic topology in active regions, quiet Sun and open field regions. An analysis of Doppler velocity time-series of the solar corona from the 10747 {\AA} Iron XIII line is performed, determining the velocity power spectrum and using it as a tool to probe wave behavior. Further, the average phase speed and density for each region are estimated and used to compute the spectra for energy density and energy flux. In addition, we assess the noise levels associated with the CoMP data, deriving analytic formulae for the uncertainty on Doppler velocity measurements and providing a comparison by estimating the noise from the data. It is found that the entire corona is replete with transverse wave behavior. The corresponding power spectra indicate that the observed velocity fluctuations are predominately generated by stochastic processes,with the spectral slope of the power varying between the different magnetic regions. Most strikingly, all power spectra reveal the presence of enhanced power occurring at ∼3 mHz, potentially implying that the excitation of coronal transverse waves by p-modes is a global phenomenon.", author = "Richard Morton and Steve Tomczyk and Rui Pinto", year = "2016", month = sep, day = "10", doi = "10.3847/0004-637X/828/2/89", language = "English", volume = "828", pages = "89", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . The Astrophysical Journal.

Morton, R. J., Mooroogen, K. (2016). Model fitting of kink waves in the solar atmosphere: Gaussian damping and time-dependence .

Morton, Richard, Banerjee, Dipankar, Chandrashekhar, K., Pant, Vaibhav, Datta, Ajanta (2016). Tornados and Transverse Oscillations during Prominence Eruption .

Weberg, M. J., Morton, R. J., McLaughlin, J. A. (2016). Automating Direct Observations of Transverse Waves in the Solar Corona .

Winebarger, A. R., Cirtain, J. W., Golub, L., Walsh, R. W., De Pontieu, B., Savage, S. L., Rachmeler, L., Kobayashi, K., Testa, P., Brooks, D., et al. (2016). The importance of high-resolution observations of the solar corona .

On the Properties of Slow MHD Sausage Waves Within Small-Scale Photospheric Magnetic Structures @article{63caa5a865a34ed5956fbe2b93d4a93c, title = "On the Properties of Slow MHD Sausage Waves Within Small-Scale Photospheric Magnetic Structures", abstract = "The presence of magnetoacoustic waves in magnetic structures in the solar atmosphere is well-documented. Applying the technique of solar magneto-seismology (SMS) allows us to infer the background properties of these structures. Here, we aim to identify properties of the observed magnetoacoustic waves and study the background properties of magnetic structures within the lower solar atmosphere. Using the Dutch Open Telescope and Rapid Oscillations in the Solar Atmosphere instruments, we captured two series of high-resolution intensity images with short cadences of two isolated magnetic pores. Combining wavelet analysis and empirical mode decomposition (EMD), we determined characteristic periods within the cross-sectional (i.e., area) and intensity time series. Then, by applying the theory of linear magnetohydrodynamics (MHD), we identified the mode of these oscillations within the MHD framework. Several oscillations have been detected within these two magnetic pores. Their periods range from 3 to 20 minutes. Combining wavelet analysis and EMD enables us to confidently find the phase difference between the area and intensity oscillations. From these observed features, we concluded that the detected oscillations can be classified as slow sausage MHD waves. Furthermore, we determined several key properties of these oscillations such as the radial velocity perturbation, the magnetic field perturbation, and the vertical wavenumber using SMS. The estimated range of the related wavenumbers reveals that these oscillations are trapped within these magnetic structures. Our results suggest that the detected oscillations are standing harmonics, and this allows us to estimate the expansion factor of the waveguides by employing SMS. The calculated expansion factor ranges from 4 to 12.", keywords = "magnetohydrodynamics (MHD), Sun: atmosphere, Sun: helioseismology, Sun: magnetic fields, Sun: oscillations, Sun: photosphere", author = "N. Freij and Ivan Dorotovi{\v c} and Richard Morton and Ruderman, \{Michael S.\} and V. Karlovsk{\'y} and Robert Erd{\'e}lyi", note = "AM requested 10-2-16 PB", year = "2016", month = jan, day = "20", doi = "10.3847/0004-637X/817/1/44", language = "English", volume = "817", pages = "44", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

N. Freij, I. Dorotovič, R. J. Morton, M. S. Ruderman, V. Karlovsk&#253;, R. Erd&#233;lyi (2016). ON THE PROPERTIES OF SLOW MHD SAUSAGE WAVES WITHIN SMALL-SCALE PHOTOSPHERIC MAGNETIC STRUCTURES . The Astrophysical Journal.

Freij, N., Dorotovič, I., Morton, R. J., Ruderman, M. S., Karlovsk&#253;, V., Erd&#233;lyi, R. (2016). On the Properties of Slow MHD Sausage Waves within Small-scale Photospheric Magnetic Structures .

Morton, R.J., Tomczyk, S., Pinto, R.F.(2016). A GLOBAL VIEW of VELOCITY FLUCTUATIONS in the CORONA below 1.3 R _o with CoMP . Astrophysical Journal. 828. (2).

Freij, N., Dorotovič, I., Morton, R.J., Ruderman, M.S., Karlovsk&#253;, V., Erd&#233;lyi, R.(2016). ON the PROPERTIES of SLOW MHD SAUSAGE WAVES WITHIN SMALL-SCALE PHOTOSPHERIC MAGNETIC STRUCTURES . Astrophysical Journal. 817. (1).

Morton, R.J., Mooroogen, K.(2016). Model fitting of kink waves in the solar atmosphere: Gaussian damping and time-dependence . Astronomy and Astrophysics. 593.

Morton, R. J., Tomczyk, S., Pinto, R. (2015). Investigating Alfvénic wave propagation in coronal open-field regions .

Multiwavelength studies of MHD waves in the solar chromosphere @article{d7bd4f832a394cc9a1be9a2c4c6ffb9a, title = "Multiwavelength studies of MHD waves in the solar chromosphere", abstract = "The chromosphere is a thin layer of the solar atmosphere that bridges the relatively cool photosphere and the intensely heated transition region and corona. Compressible and incompressible waves propagating through the chromosphere can supply significant amounts of energy to the interface region and corona. In recent years an abundance of high-resolution observations from state-of-the-art facilities have provided new and exciting ways of disentangling the characteristics of oscillatory phenomena propagating through the dynamic chromosphere. Coupled with rapid advancements in magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly investigate the role waves play in supplying energy to sustain chromospheric and coronal heating. Here, we review the recent progress made in characterising, categorising and interpreting oscillations manifesting in the solar chromosphere, with an impetus placed on their intrinsic energetics.", keywords = "Sun: compressible waves, Sun: incompressible waves, Sun: chromosphere, Sun: spicules, Plasma wave heating", author = "David Jess and Richard Morton and Gary Verth and Viktor Fedun and Samuel Grant and Ioannis Giagkiozis", year = "2015", month = jul, doi = "10.1007/s11214-015-0141-3", language = "English", volume = "190", pages = "103--161", journal = "Space Science Reviews", issn = "0038-6308", publisher = "Springer", number = "1-4", } . Space Science Reviews.

Jess, D. B., Morton, R. J., Verth, G., Fedun, V., Grant, S. D. T., Giagkiozis, I. (2015). Multiwavelength Studies of MHD Waves in the Solar Chromosphere. An Overview of Recent Results .

S. D. T. Grant, D. B. Jess, M. G. Moreels, R. J. Morton, D. J. Christian, I. Giagkiozis, G. Verth, V. Fedun, P. H. Keys, T. Van Doorsselaere, et al.(2015). WAVE DAMPING OBSERVED IN UPWARDLY PROPAGATING SAUSAGE-MODE OSCILLATIONS CONTAINED WITHIN A MAGNETIC PORE . The Astrophysical Journal. 806. (1). p. 132. {IOP} Publishing

Wave damping observed in upwardly propagating sausage-mode oscillations contained within a magnetic pore @article{e8691f8da3d2499abdc42583b6d83e74, title = "Wave damping observed in upwardly propagating sausage-mode oscillations contained within a magnetic pore", abstract = "We present observational evidence of compressible MHD wave modes propagating from the solar photosphere through to the base of the transition region in a solar magnetic pore. High cadence images were obtained simultaneously across four wavelength bands using the Dunn Solar Telescope. Employing Fourier and wavelet techniques, sausage-mode oscillations displaying significant power were detected in both intensity and area fluctuations. The intensity and area fluctuations exhibit a range of periods from 181 to 412 s, with an average period similar to 290 s, consistent with the global p-mode spectrum. Intensity and area oscillations present in adjacent bandpasses were found to be out of phase with one another, displaying phase angles of 6 degrees.12, 5 degrees.82, and 15 degrees.97 between the 410 angstrom continuum-G-band, G-band-Na I D1, and Na I D-1-Ca II K heights, respectively, reiterating the presence of upwardly propagating sausage-mode waves. A phase relationship of similar to 0 degrees between same-bandpass emission and area perturbations of the pore best categorizes the waves as belonging to the {"}slow{"} regime of a dispersion diagram. Theoretical calculations reveal that the waves are surface modes, with initial photospheric energies in excess of 35,000 W m(-2). The wave energetics indicate a substantial decrease in energy with atmospheric height, confirming that magnetic pores are able to transport waves that exhibit appreciable energy damping, which may release considerable energy into the local chromospheric plasma.", keywords = "magnetohydrodynamics (MHD), Sun: chromosphere, Sun: oscillations, Sun: photosphere", author = "Samuel Grant and David Jess and Moreels, \{M. G.\} and Richard Morton and Damian Christian and Ioannis Giagkiozis and Gary Verth and Viktor Fedun and Peter Keys and \{van Doorsselaere\}, Tom and Robert Erd{\'e}lyi", year = "2015", month = jun, day = "10", doi = "10.1088/0004-637X/806/1/132", language = "English", volume = "806", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

Morton, R.J., Tomczyk, S., Pinto, R.(2015). Investigating Alfvénic wave propagation in coronal open-field regions . Nature Communications. 6.

Jess, D.B., Morton, R.J., Verth, G., Fedun, V., Grant, S.D.T., Giagkiozis, I.(2015). Multiwavelength Studies of MHD Waves in the Solar Chromosphere: An Overview of Recent Results . Space Science Reviews. 190. (1-4). p. 103-161.

Grant, S.D.T., Jess, D.B., Moreels, M.G., Morton, R.J., Christian, D.J., Giagkiozis, I., Verth, G., Fedun, V., Keys, P.H., Van Doorsselaere, T., et al.(2015). WAVE DAMPING OBSERVED in UPWARDLY PROPAGATING SAUSAGE-MODE OSCILLATIONS CONTAINED WITHIN A MAGNETIC PORE . Astrophysical Journal. 806. (1).

Richard Morton, Steve Tomczyk, Rui Pinto(2015). Investigating Alfvénic wave propagation in coronal open-field regions . Nature Communications. 6. p. 7813. Nature Research

First direct measurements of transverse waves in solar polar plumes using SDO/AIA @article{33f859beaf234c1c906871b200eb6cde, title = "First direct measurements of transverse waves in solar polar plumes using SDO/AIA", abstract = "There is intense interest in determining the precise contribution of Alfv{\'e}nic waves propagating along solar structures to the problems of coronal heating and solar wind acceleration. Since the launch of SDO/AIA, it has been possible to resolve transverse oscillations in off-limb solar polar plumes and recently McIntosh et al. concluded that such waves are energetic enough to play a role in heating the corona and accelerating the fast solar wind. However, this result is based on comparisons to Monte Carlo simulations and confirmation via direct measurements is still outstanding. Thus, this Letter reports on the first direct measurements of transverse wave motions in solar polar plumes. Over a four hour period, we measure the transverse displacements, periods, and velocity amplitudes of 596 distinct oscillations observed in the 171 {\AA} channel of SDO/AIA. We find a broad range of non-uniformly distributed parameter values which are well described by log-normal distributions with peaks at 234 km, 121 s, and 8 km s\textasciicircum{}−1, and mean and standard deviations of 407 ± 297 km, 173 ± 118 s, and 14 ± 10 km s\textasciicircum{}−1. Within standard deviations, our direct measurements are broadly consistent with previous results. However, accounting for the whole of our observed non-uniform parameter distribution we calculate an energy flux of 9–24 W m\textasciicircum{}−2, which is 4–10 times below the energy requirement for solar wind acceleration. Hence, our results indicate that transverse magnetohydrodynamic waves as resolved by SDO/AIA cannot be the dominant energy source for fast solar wind acceleration in the open-field corona.", author = "Jonathan Thurgood and Richard Morton and James McLaughlin", year = "2014", month = jul, day = "20", doi = "10.1088/2041-8205/790/1/L2", language = "English", volume = "790", journal = "The Astrophysical Journal Letters", issn = "2041-8205", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal Letters.

J. O. Thurgood, R. J. Morton, J. A. McLaughlin(2014). FIRST DIRECT MEASUREMENTS OF TRANSVERSE WAVES IN SOLAR POLAR PLUMES USING SDO /AIA . The Astrophysical Journal. 790. (1). p. L2. {IOP} Publishing

High-resolution observations of active region moss and its dynamics @article{58483cd57a094df29676525fa42d1f8a, title = "High-resolution observations of active region moss and its dynamics", abstract = "The High Resolution Coronal Imager has provided the sharpest view of the EUV corona to date. In this paper, we exploit its impressive resolving power to provide the first analysis of the fine-scale structure of moss in an active region. The data reveal that the moss is made up of a collection of fine threads that have widths with a mean and standard deviation of 440 ± 190 km (FWHM). The brightest moss emission is located at the visible head of the fine-scale structure and the fine structure appears to extend into the lower solar atmosphere. The emission decreases along the features, implying that the lower sections are most likely dominated by cooler transition region plasma. These threads appear to be the cool, lower legs of the hot loops. In addition, the increased resolution allows for the first direct observation of physical displacements of the moss fine structure in a direction transverse to its central axis. Some of these transverse displacements demonstrate periodic behavior, which we interpret as a signature of kink (Alfv{\'e}nic) waves. Measurements of the properties of the transverse motions are made and the wave motions have means and standard deviations of 55 ± 37 km for the transverse displacement amplitude, 77 ± 33 s for the period, and 4.7 ± 2.5 km s–1 for the velocity amplitude. The presence of waves in the transition region of hot loops could have important implications for the heating of active regions.", author = "Richard Morton and James McLaughlin", year = "2014", month = jul, doi = "10.1088/0004-637X/789/2/105", language = "English", volume = "789", pages = "105", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . The Astrophysical Journal.

R. J. Morton, J. A. McLaughlin(2014). HIGH-RESOLUTION OBSERVATIONS OF ACTIVE REGION MOSS AND ITS DYNAMICS . The Astrophysical Journal. 789. (2). p. 105. {IOP} Publishing

Morton, Richard, Alexander, Caroline, Winebarger, Amy R., Savage, Sabrina (2014). Dynamic moss observed with Hi-C .

Magneto-seismological insights into the penumbral chromosphere and evidence for wave damping in spicules @article{fbda06c1937c4afe834035bc34296636, title = "Magneto-seismological insights into the penumbral chromosphere and evidence for wave damping in spicules", abstract = "Aims: The observation of propagating magneto-hydrodynamic kink waves in magnetic structures and measurement of their properties (amplitude, phase speed) can be used to diagnose the plasma conditions in the neighbourhood of the magnetic structure via magneto-seismology. We aim to reveal properties of the chromosphere/transition region above the sunspot penumbra using this technique. Methods: Hinode SOT observed a sunspot as it was crossing over the limb, providing a unique side on view of the atmosphere above a sunspot. The presence of large spicule-like jets is evident in Ca ii H images. The jets are found to support transverse wave motions that displace the central axis of the spicules, which can be interpreted as the kink wave. The properties of a specific wave event are measured and used to determine the magnetic and density stratification along the structure. In addition, we measure the width of the spicule and the intensity profile along the structure in order to provide a test for the magneto-seismological results. Results: The measurements of the wave properties reveal an initial rapid increase in amplitude with height above the solar surface, followed by a decrease in amplitude. The magneto-seismological inversions suggests this initial increase corresponds to large changes in density and magnetic field strength. In addition, we provide the first measurements of spicule width with height, which confirm that the spicule under goes rapid expansion. The measured rates of expansion show good agreement with the results from the magneto-seismology. The observed rapid variations in plasma parameters are suggested to be partly due to the presence of a gravitational stratified, ambient atmosphere. Combining width measurements with phase speed measurements implies the observed decrease in wave amplitude at greater heights can be explained by wave damping. Hence, we provide the first direct evidence of wave damping in chromospheric spicules and the quality factor of the damping is found to be significantly smaller than estimated coronal values.", author = "Richard Morton", year = "2014", month = jun, doi = "10.1051/0004-6361/201423718", language = "English", volume = "566", pages = "90", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", } . Astronomy & Astrophysics.

The generation and damping of propagating MHD kink waves in the solar atmosphere @article{ab0357f8d9604ea0877fe7ad883f8cf5, title = "The generation and damping of propagating MHD kink waves in the solar atmosphere", abstract = "The source of the non-thermal energy required for the heating of the upper solar atmosphere to temperatures in excess of a million degrees and the acceleration of the solar wind to hundreds of kilometers per second is still unclear. One such mechanism for providing the required energy flux is incompressible torsional Alfven and kink magnetohydrodynamic (MHD) waves, which are magnetically dominated waves supported by the Sun's pervasive and complex magnetic field. In particular, propagating MHD kink waves have recently been observed to be ubiquitous throughout the solar atmosphere, but, until now, critical details of the transport of the kink wave energy throughout the Sun's atmosphere were lacking. Here, the ubiquity of the waves is exploited for statistical studies in the highly dynamic solar chromosphere. This large-scale investigation allows for the determination of the chromospheric kink wave velocity power spectra, a missing link necessary for determining the energy transport between the photosphere and corona. Crucially, the power spectra contain evidence for horizontal photospheric motions being an important mechanism for kink wave generation in the quiescent Sun. In addition, a comparison with measured coronal power spectra is provided for the first time, revealing frequency-dependent transmission profiles, suggesting that there is enhanced damping of kink waves in the lower corona.", author = "Richard Morton and Gary Verth and Andrew Hillier and Robert Erd{\'e}lyi", year = "2014", month = mar, day = "20", doi = "10.1088/0004-637X/784/1/29", language = "English", volume = "784", pages = "29", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

The dynamical behaviour of a jet in an on-disk coronal hole observed with AIA/SDO @article{2e5468d2ce774321811ce988f8e9a5ae, title = "The dynamical behaviour of a jet in an on-disk coronal hole observed with AIA/SDO", abstract = "Aims. Extreme ultraviolet (EUV) jets situated in coronal holes are thought to play an important role in supplying heated material to the corona and solar wind. The multi-wavelength capabilities and high signal-to-noise ratio of detectors on board the Solar Dynamic Observatory (SDO) allow for detailed study of these jets{\textquoteright} evolution. We aim to exploit SDO{\textquoteright}s capabilities to reveal information on the jet dynamics and to obtain estimates for plasma properties associated with the jets. Methods. We studied the dynamics of an EUV jet with SDO at a coronal hole boundary. The details of the jet evolution are discussed and measurements of the jet{\textquoteright}s parameters, e.g. length, width, life time, and outward speed, are obtained. Furthermore, automated emission measure analysis is exploited to determine estimates for the temperature and density of the jet. A propagating transverse wave supported by the jet spire is also observed. Measurements of the wave properties are exploited for magneto-seismology and are used in conjunction with the emission measure results to estimate the magnetic field strength of the jet. Results. We present a detailed description of the jet{\textquoteright}s evolution, with new evidence of plasma flows, prior to the jet{\textquoteright}s initiation, along the loops at the base of the jet and also find further evidence that flows along the jet spire consist of multiple, quasi-periodic small-scale plasma ejection events. In addition, spectroscopic analysis reveal that the jet has temperatures of log 5.89 ± 0.08 K and electron densities of log 8.75 ± 0.05 cm-3. Measured properties of the transverse wave provide evidence that a strong damping of the wave occurs as it propagates along the jet spire with speeds of \textasciitilde{}110 km s-1. The magneto-seismological inversion of the wave parameters provides values of B = 1.21 ± 0.2 G along the jet spire, which is in line with previous estimates for open fields in coronal holes.", author = "K. Chandrashekhar and Richard Morton and Dipankar Banerjee and Girjesh Gupta", year = "2014", month = feb, doi = "10.1051/0004-6361/201322408", language = "English", volume = "562", pages = "A98", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", } . Astronomy & Astrophysics.

Morton, Richard, Banerjee, Dipankar, Chandrashekhar, K. (2014). Transverse Oscillations observed in a Jet and coronal seismology .

Chandrashekhar, K., Morton, R.J., Banerjee, D., Gupta, G.R.(2014). The dynamical behaviour of a jet in an on-disk coronal hole observed with AIA/SDO . Astronomy and Astrophysics. 562.

Morton, Richard (2014). Magneto-seismological insights into the penumbral chromosphere and evidence for wave damping in chromospheric wave-guides .

Morton, R. J.(2014). Magneto-seismological insights into the penumbral chromosphere and evidence for wave damping in spicules . Astronomy & Astrophysics. 566.

Morton, R.J.(2014). Magneto-seismological insights into the penumbral chromosphere and evidence for wave damping in spicules . Astronomy and Astrophysics. 566.

Morton, R. J., Verth, G., Hillier, A., Erdelyi, R.(2014). THE GENERATION AND DAMPING OF PROPAGATING MHD KINK WAVES IN THE SOLAR ATMOSPHERE . Astrophysical Journal. 784. (1).

Morton, R.J., Verth, G., Hillier, A., Erd&#233;lyi, R.(2014). The generation and damping of propagating MHD kink waves in the solar atmosphere . Astrophysical Journal. 784. (1).

Chandrashekhar, K. y, Morton, R. J., Banerjee, D., Gupta, G. R.(2014). The dynamical behaviour of a jet in an on-disk coronal hole observed with AIA/SDO . Astronomy & Astrophysics. 562.

Morton, R.J., McLaughlin, J.A.(2014). High-resolution observations of active region moss and its dynamics . Astrophysical Journal. 789. (2).

Thurgood, J. O., Morton, R. J., McLaughlin, J. A.(2014). FIRST DIRECT MEASUREMENTS OF TRANSVERSE WAVES IN SOLAR POLAR PLUMES USING SDO/AIA . Astrophysical Journal Letters. 790. (1).

Thurgood, J.O., Morton, R.J., McLaughlin, J.A.(2014). First direct measurements of transverse waves in solar polar plumes using SDO/AIA . Astrophysical Journal Letters. 790. (1).

Morton, R. J., McLaughlin, J. A.(2014). HIGH-RESOLUTION OBSERVATIONS OF ACTIVE REGION MOSS AND ITS DYNAMICS . Astrophysical Journal. 789. (2).

A statistical study of transverse oscillations in a quiescent prominence @article{fae9b99bb55040b8b09fe217af703592, title = "A statistical study of transverse oscillations in a quiescent prominence", abstract = "The launch of the Hinode satellite has allowed for seeing-free observations at high-resolution and high-cadence making it well suited to study the dynamics of quiescent prominences. In recent years it has become clear that quiescent prominences support small-amplitude transverse oscillations, however, sample sizes are usually too small for general conclusions to be drawn. We remedy this by providing a statistical study of transverse oscillations in vertical prominence threads. Over a 4 hr period of observations it was possible to measure the properties of 3436 waves, finding periods from 50 to 6000 s with typical velocity amplitudes ranging between 0.2 and 23 km s–1. The large number of observed waves allows the determination of the frequency dependence of the wave properties and derivation of the velocity power spectrum for the transverse waves. For frequencies less than 7 mHz, the frequency dependence of the velocity power is consistent with the velocity power spectra generated from observations of the horizontal motions of magnetic elements in the photosphere, suggesting that the prominence transverse waves are driven by photospheric motions. However, at higher frequencies the two distributions significantly diverge, with relatively more power found at higher frequencies in the prominence oscillations. These results highlight that waves over a large frequency range are ubiquitous in prominences, and that a significant amount of the wave energy is found at higher frequency.", keywords = "magnetohydrodynamics (MHD), Sun: filaments, prominences, waves", author = "Andrew Hillier and Richard Morton and Robert Erd{\'e}lyi", year = "2013", month = dec, day = "20", doi = "10.1088/2041-8205/779/2/L16", language = "English", volume = "779", journal = "The Astrophysical Journal Letters", issn = "2041-8205", publisher = "American Astronomical Society", number = "2", } . The Astrophysical Journal Letters.

Characteristics of transverse waves in chromospheric mottles @article{ba6a46100c83486887f9707fe1815840, title = "Characteristics of transverse waves in chromospheric mottles", abstract = "Using data obtained by the high temporal and spatial resolution Rapid Oscillations in the Solar Atmosphere instrument on the Dunn Solar Telescope, we investigate at an unprecedented level of detail transverse oscillations in chromospheric fine structures near the solar disk center. The oscillations are interpreted in terms of propagating and standing magnetohydrodynamic kink waves. Wave characteristics including the maximum transverse velocity amplitude and the phase speed are measured as a function of distance along the structure's length. Solar magnetoseismology is applied to these measured parameters to obtain diagnostic information on key plasma parameters (e.g., magnetic field, density, temperature, flow speed) of these localized waveguides. The magnetic field strength of the mottle along the \textasciitilde{}2 Mm length is found to decrease by a factor of 12, while the local plasma density scale height is \textasciitilde{}280 ± 80 km.", author = "David Kuridze and Gary Verth and Mihalis Mathioudakis and Robert Erd{\'e}lyi and David Jess and Richard Morton and Damian Christian and Francis Keenan", year = "2013", month = dec, day = "10", doi = "10.1088/0004-637X/779/1/82", language = "English", volume = "779", pages = "82", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

Hi-C and AIA observations of transverse magnetohydrodynamic waves in active regions @article{b97ae0b7aee74128a907d24830e8de6f, title = "Hi-C and AIA observations of transverse magnetohydrodynamic waves in active regions", abstract = "The recent launch of the High resolution Coronal imager (Hi-C) provided a unique opportunity of studying the EUV corona with unprecedented spatial resolution. We utilize these observations to investigate the properties of low-frequency (50−200 s) active region transverse waves, whose omnipresence had been suggested previously. The five-fold improvement in spatial resolution over SDO/AIA reveals coronal loops with widths 150−310 km and that these loops support transverse waves with displacement amplitudes", keywords = "Sun: corona, Sun: chromosphere, waves, magnetohydrodynamics (MHD)", author = "Richard Morton and James McLaughlin", year = "2013", month = may, day = "22", doi = "10.1051/0004-6361/201321465", language = "English", volume = "553", pages = "L10", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", } . Astronomy & Astrophysics.

Evidence for the photospheric excitation of incompressible chromospheric waves @article{66ec69e6542b46c08f12bdd13f363eb8, title = "Evidence for the photospheric excitation of incompressible chromospheric waves", abstract = "Observing the excitation mechanisms of incompressible transverse waves is vital for determining how energy propagates through the lower solar atmosphere. We aim to show the connection between convectively driven photospheric flows and incompressible chromospheric waves. The observations presented here show the propagation of incompressible motion through the quiet lower solar atmosphere, from the photosphere to the chromosphere. We determine photospheric flow vectors to search for signatures of vortex motion and compare results to photospheric flows present in convective simulations. Further, we search for the chromospheric response to vortex motions. Evidence is presented that suggests incompressible waves can be excited by the vortex motions of a strong magnetic flux concentration in the photosphere. A chromospheric counterpart to the photospheric vortex motion is also observed, presenting itself as a quasi-periodic torsional motion. Fine-scale, fibril structures that emanate from the chromospheric counterpart support transverse waves that are driven by the observed torsional motion. A new technique for obtaining details of transverse waves from time-distance diagrams is presented and the properties of transverse waves (e.g., amplitudes and periods) excited by the chromospheric torsional motion are measured.", keywords = "magnetohydrodynamics (MHD), Sun: chromosphere, Sun: photosphere, waves", author = "Richard Morton and Gary Verth and Viktor Fedun and Sergiy Shelyag", year = "2013", month = may, doi = "10.1088/0004-637X/768/1/17", language = "English", volume = "768", pages = "17", journal = "The Astronomical Journal", issn = "0004-6256", publisher = "American Astronomical Society", number = "1", } . The Astronomical Journal.

Morton, Richard, Verth, Gary, Erdelyi, Robertus, Srivastava, Abhi (2013). SDO/AIA observations of periodic and quasi-periodic phenomenon associated with an EUV jet .

Morton, R. J., McLaughlin, J. A.(2013). Hi-C and AIA observations of transverse magnetohydrodynamic waves in active regions (vol 553, L10, 2013) . Astronomy & Astrophysics. 556.

Morton, R.J., McLaughlin, J.A.(2013). Hi-C and AIA observations of transverse magnetohydrodynamic waves in active regions . Astronomy and Astrophysics. 553.

Morton, R. J., Verth, G., Fedun, V., Shelyag, S., Erdelyi, R.(2013). EVIDENCE FOR THE PHOTOSPHERIC EXCITATION OF INCOMPRESSIBLE CHROMOSPHERIC WAVES . Astrophysical Journal. 768. (1).

Morton, R.J., Verth, G., Fedun, V., Shelyag, S., Erd&#233;lyi, R.(2013). Evidence for the photospheric excitation of incompressible chromospheric waves . Astrophysical Journal. 768. (1).

Hillier, A., Morton, R. J., Erdelyi, R.(2013). A STATISTICAL STUDY OF TRANSVERSE OSCILLATIONS IN A QUIESCENT PROMINENCE . Astrophysical Journal Letters. 779. (2).

Kuridze, D., Verth, G., Mathioudakis, M., Erdelyi, R., Jess, D. B., Morton, R. J., Christian, D. J., Keenan, F. P.(2013). CHARACTERISTICS OF TRANSVERSE WAVES IN CHROMOSPHERIC MOTTLES . Astrophysical Journal. 779. (1).

Kuridze, D., Verth, G., Mathioudakis, M., Erd&#233;lyi, R., Jess, D.B., Morton, R.J., Christian, D.J., Keenan, F.P.(2013). Characteristics of transverse waves in chromospheric mottles . Astrophysical Journal. 779. (1).

Morton, R. J., McLaughlin, J. A.(2013). Hi-C and AIA observations of transverse magnetohydrodynamic waves in active regions . Astronomy & Astrophysics. 553.

Observations of ubiquitous compressive waves in the Sun’s chromosphere @article{5754f135826943d59ba0a27f6a9cb21b, title = "Observations of ubiquitous compressive waves in the Sun{\textquoteright}s chromosphere", abstract = "The details of the mechanism(s) responsible for the observed heating and dynamics of the solar atmosphere still remain a mystery. Magnetohydrodynamic waves are thought to have a vital role in this process. Although it has been shown that incompressible waves are ubiquitous in off-limb solar atmospheric observations, their energy cannot be readily dissipated. Here we provide, for the first time, on-disk observation and identification of concurrent magnetohydrodynamic wave modes, both compressible and incompressible, in the solar chromosphere. The observed ubiquity and estimated energy flux associated with the detected magnetohydrodynamic waves suggest the chromosphere is a vast reservoir of wave energy with the potential to meet chromospheric and coronal heating requirements. We are also able to propose an upper bound on the flux of the observed wave energy that is able to reach the corona based on observational constraints, which has important implications for the suggested mechanism(s) for quiescent coronal heating.", author = "Richard Morton and Gary Verth and David Jess and David Kuridze and Ruderman, \{Michael S.\} and Mihalis Mathioudakis and Robert Erd{\'e}lyi", year = "2012", month = dec, day = "27", doi = "10.1038/ncomms2324", language = "English", volume = "3", journal = "Nature Communications", issn = "2041-1723", publisher = "Nature Research", } . Nature Communications.

Chromospheric jets around the edges of sunspots @article{643287229e184b33b6413d9bcf1149f6, title = "Chromospheric jets around the edges of sunspots", abstract = "Aims. Evidence is beginning to be put forward that demonstrates the role of the chromosphere in supplying energy and mass to the corona. We aim to asses the role of chromospheric jets in active region dynamics. Methods. Using a combination of the Hinode/SOT Ca II H and TRACE 1550 {\AA} and 1600 {\AA} filters we examine chromospheric jets situated at the edge of a sunspot. Results. Analysis reveals a near continuous series of jets, that raise chromospheric material into the low corona above a sunspot. The jets have average rise speeds of 30 km/s and a range of 10−100 km/s. Enhanced emission observed at the jets leading edge suggests the formation of a shock front. Increased emission in TRACE bandpasses above the sunspot and the disappearance of the jets from the Ca II filter suggests that some of the chromospheric jet material is at least heated to ∼ 0.1 MK. The evidence suggests that the jets could be a mechanism which provides a steady, low-level heating for active region features.", keywords = "magnetohydrodynamics (MHD), plasmas, shock waves, Sun: chromosphere, sunspots", author = "Richard Morton", year = "2012", month = jul, doi = "10.1051/0004-6361/201219137", language = "English", volume = "543", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", number = "A6", } . Astronomy & Astrophysics.

Srivastava, Abhishek K., Von Fay-Siebenburgen (Erd&#233;lyi), Robert, Fedun, Viktor, Ravindra, B., Morton, R. J. (2012). Observations of Magneto-acoustic Waves above the Intensity Enhanced Quiet Sun Regions from Hinode/SOT .

Observations of quasi-periodic phenomena associated with a large blowout solar jet @article{ec40db426a8c4b8a9d4433a5e6d9c220, title = "Observations of quasi-periodic phenomena associated with a large blowout solar jet", abstract = "Aims: A variety of periodic phenomena have been observed in conjunction with large solar jets. We aim to find further evidence for (quasi-)periodic behaviour in solar jets and determine what the periodic behaviour can tell us about the excitation mechanism and formation process of the large solar jet. Methods: Using the 304 {\AA} (He-II), 171 {\AA} (Fe IX), 193 {\AA} (Fe XII/XXIV) and 131 {\AA} (Fe VIII/XXI) filters onboard the Solar Dynamic Observatory (SDO) Atmospheric Imaging Assembly (AIA), we investigate the intensity oscillations associated with a solar jet. Results: Evidence is provided for multiple magnetic reconnection events occurring between a pre-twisted, closed field and open field lines. Components of the jet are seen in multiple SDO/AIA filters covering a wide range of temperatures, suggesting the jet can be classified as a blowout jet. Two bright, elongated features are observed to be co-spatial with the large jet, appearing at the jet's footpoints. Investigation of these features reveal they are defined by multiple plasma ejections. The ejecta display (quasi-)periodic behaviour on timescales of 50 s and have rise velocities of 40-150 km/s along the open field lines. Due to the suggestion that the large jet is reconnection-driven and the observed properties of the ejecta, we further propose that these ejecta events are similar to type-II spicules. The bright features also display (quasi)-periodic intensity perturbations on the timescale of 300 s. Possible explanations for the existence of the (quasi-)periodic perturbations in terms of jet dynamics and the response of the transition region are discussed.", author = "Richard Morton and Abhishek Srivastava and Robert Erd{\'e}lyi", year = "2012", month = jun, doi = "10.1051/0004-6361/201117218", language = "English", volume = "542", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", number = "A70", } . Astronomy & Astrophysics.

Transverse oscillations in chromospheric mottles @article{7b7f404ce1d2482a8921f9b0626efe4d, title = "Transverse oscillations in chromospheric mottles", abstract = "A number of recent investigations have revealed that transverse waves are ubiquitous in the solar chromosphere. The vast majority of these have been reported in limb spicules and active region fibrils. We investigate long-lived, quiet-Sun, on-disk features such as chromospheric mottles (jet-like features located at the boundaries of supergranular cells) and their transverse motions. The observations were obtained with the Rapid Oscillations in the Solar Atmosphere instrument at the Dunn Solar Telescope. The data set is comprised of simultaneous imaging in the Hα core, Ca II K, and G band of an on-disk quiet-Sun region. Time-distance techniques are used to study the characteristics of the transverse oscillations. We detect over 40 transverse oscillations in both bright and dark mottles, with periods ranging from 70 to 280 s, with the most frequent occurrence at \textasciitilde{}165 s. The velocity amplitudes and transverse displacements exhibit characteristics similar to limb spicules. Neighboring mottles oscillating in-phase are also observed. The transverse oscillations of individual mottles are interpreted in terms of magnetohydrodynamic kink waves. Their estimated periods and damping times are consistent with phase mixing and resonant mode conversion.", keywords = "magnetohydrodynamics (MHD), Sun: atmosphere, Sun: chromosphere, Sun: oscillations, magnetic fields, waves", author = "Richard Morton and David Kuridze and Robert Erd{\'e}lyi and Gareth Dorrian and Mihalis Mathioudakis and David Jess and Francis Keenan", year = "2012", month = may, doi = "10.1088/0004-637X/750/1/51", language = "English", volume = "750", pages = "51", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

Determination of sub-resolution structure of a jet by solar magnetoseismology @article{d16396e5bc554c009df75e0714d2ed9f, title = "Determination of sub-resolution structure of a jet by solar magnetoseismology", abstract = "A thin dark thread is observed in a UV/EUV solar jet in the 171A, 193A and 211A and partially in 304A. The dark thread appears to originate in the chromosphere but its temperature does not appear to lie within the passbands of the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). We therefore implement solar magnetoseismology to estimate the plasma parameters of the dark thread. A propagating fast kink (transverse) wave is observed to travel along the dark thread. The wave is tracked over a range of \textasciitilde{} 7000 km by placing multiple slits along the axis of the dark thread. The phase speed and amplitude of the wave are estimated and magnetoseismological theory is employed to determine the plasma parameters. We are able to estimate the plasma temperature, density gradient, magnetic field gradient and sub-resolution expansion of the dark thread. The dark thread is found to be cool, T \textasciitilde{} 3x10\textasciicircum{}4 K with both strong density and magnetic field gradients. The expansion of the flux tube along its length is \textasciitilde{} 300-400 km.", keywords = "magnetic fields, magnetohydrodynamics (MHD), plasmas, Sun: oscillations", author = "Richard Morton and Gary Verth and James McLaughlin and Robert Erd{\'e}lyi", year = "2012", month = jan, doi = "10.1088/0004-637X/744/1/5", language = "English", volume = "744", pages = "1--11", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

Kuridze, D., Morton, R. J., Erdelyi, R., Dorrian, G. D., Mathioudakis, M., Jess, D. B., Keenan, F. P.(2012). TRANSVERSE OSCILLATIONS IN CHROMOSPHERIC MOTTLES . Astrophysical Journal. 750. (1).

Kuridze, D., Morton, R.J., Erd&#233;lyi, R., Dorrian, G.D., Mathioudakis, M., Jess, D.B., Keenan, F.P.(2012). Transverse oscillations in chromospheric mottles . Astrophysical Journal. 750. (1).

Morton, R. J., Verth, G., McLaughlin, J. A., Erdelyi, R.(2012). DETERMINATION OF SUB-RESOLUTION STRUCTURE OF A JET BY SOLAR MAGNETOSEISMOLOGY . Astrophysical Journal. 744. (1).

Morton, R.J., Verth, G., McLaughlin, J.A., Erd&#233;lyi, R.(2012). Determination of sub-resolution structure of a jet by solar magnetoseismology . Astrophysical Journal. 744. (1).

Morton, R. J., Srivastava, A. K., Erdelyi, R.(2012). Observations of quasi-periodic phenomena associated with a large blowout solar jet . Astronomy & Astrophysics. 542.

Morton, R.J., Srivastava, A.K., Erd&#233;lyi, R.(2012). Observations of quasi-periodic phenomena associated with a large blowout solar jet . Astronomy and Astrophysics. 542.

Morton, R.J.(2012). Chromospheric jets around the edges of sunspots . Astronomy and Astrophysics. 543.

Morton, R. J.(2012). Chromospheric jets around the edges of sunspots . Astronomy & Astrophysics. 543.

Morton, R. J.Verth, G.Jess, D. B. Kuridze, D. Ruderman, M. S.Mathioudakis, M. Erdelyi, R.(2012). Observations of ubiquitous compressive waves in the Sun's chromosphere . Nature Communications. 3. p. 1315.

Morton, R.J., Verth, G., Jess, D.B., Kuridze, D., Ruderman, M.S., Mathioudakis, M., Erd&#233;lyi, R.(2012). Observations of ubiquitous compressive waves in the Sun's chromosphere . Nature Communications. 3.

Torsional Alfvén waves: magneto-seismology in static and dynamic coronal plasmas @article{f99a8e5a2409404785312650534aa1e8, title = "Torsional Alfv{\'e}n waves: magneto-seismology in static and dynamic coronal plasmas", abstract = "Aims: We study the properties of torsional Alfv{\'e}n waves in coronal loops so that they may be exploited for coronal seismological applications. Methods: The governing equation is obtained for standing torsional Alfv{\'e}n waves of a dynamic, gravitationally stratified plasma. The footpoints are assumed to obey line-tying conditions necessary for standing oscillations. Solutions are found in a number of different but typical scenarios to demonstrate the possibilities for both temporal and spatial magneto-seismology exploitation of waveguides with the standing torsional Alfv{\'e}n oscillations. Results: It is found that the frequency of the standing Alfv{\'e}n oscillation increases as the stratification of the plasma increases. The ratio of the periods of the fundamental modeand the first overtone is also found to change as the stratification of the plasma increases. Further, the eigenfunctions of the higher overtones of the standing oscillations are found to experience a shift of their anti-nodes. The influence of a dynamic plasma on the amplitudes of the mode is also investigated. The amplitude of the torsional Alfv{\'e}n mode is found to increase as the plasma within the coronal loop experiences cooling.", keywords = "magnetohydrodynamics (MHD), plasmas, Sun: corona, waves", author = "Richard Morton and Ruderman, \{Michael S.\} and Robert Erd{\'e}lyi", year = "2011", month = oct, doi = "10.1051/0004-6361/201117020", language = "English", volume = "534", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", number = "A27", } . Astronomy & Astrophysics.

Damping of longitudinal magneto–acoustic oscillations in slowly varying coronal plasma @article{70e65bff80e248a68ef59adc1624d675, title = "Damping of longitudinal magneto–acoustic oscillations in slowly varying coronal plasma", abstract = "We investigate the propagation of MHD waves in a magnetised plasma in a weakly stratified atmosphere, representative of hot coronal loops. In most earlier studies, a time-independent equilibrium was considered. Here we abandon this restriction and allow the equilibrium to develop as a function of time. In particular, the background plasma is assumed to be cooling due to thermal conduction. The cooling is assumed to occur on a time scale greater than the characteristic travel times of the perturbations. We investigate the influence of cooling of the background plasma on the properties of magneto–acoustic waves. The MHD equations are reduced to a 1D system modelling magneto–acoustic modes propagating along a dynamically cooling coronal loop. A time-dependent dispersion relation that describes the propagation of the magneto–acoustic waves is derived using the WKB theory. An analytic solution for the time-dependent amplitude of waves is obtained, and the method of characteristics is used to find an approximate analytical solution. Numerical calculations of the analytically derived solutions are obtained to give further insight into the behaviour of the MHD waves in a system with a variable, time-dependent background. The results show that there is a strong damping of MHD waves and the damping also appears to be independent of the position along the loop. Studies of MHD wave behaviour in a time-dependent backgrounds seem to be a fundamental and very important next step in the development of MHD wave theory that is applicable to a wide range of situations in solar physics.", keywords = "Magnetohydrodynamics (MHD), plasmas, sun: corona, waves", author = "Robert Erd{\'e}lyi and Kalil Al-Ghafri and Richard Morton", year = "2011", month = aug, doi = "10.1007/s11207-011-9795-5", language = "English", volume = "272", pages = "73", journal = "Solar Physics", issn = "0038-0938", publisher = "Springer", number = "1", } . Solar Physics.

Kink and fluting modes of stratified coronal magnetic loops with elliptical cross-sections @article{eb5c5e8a2a82441ca58b6b6492dec518, title = "Kink and fluting modes of stratified coronal magnetic loops with elliptical cross-sections", abstract = "Aims. We study kink and fluting oscillations of a straight magnetic tube with an elliptic cross-section and density varying along the tube. Methods. The governing equations for kink and fluting modes in the thin tube approximation are derived. We found that there are two kink modes, polarised along the semimajor and semiminor axes of the elliptic cross-section. We have shown that the ratio of frequencies of the first overtone and fundamental mode is the same for both kink modes and independent of the ratio of the ellipse axes. Results. On the basis of this result we concluded that the estimates of the atmospheric scale height obtained using simultaneous observations of the fundamental mode and first overtone of the coronal loop kink oscillations are independent of the ellipticity of the loop cross-section.", keywords = "magnetohydrodynamics (MHD), plasmas, sun: corona, sun: oscillations, waves", author = "Morton, \{R. J.\} and Ruderman, \{M. S.\}", year = "2011", month = mar, day = "1", doi = "10.1051/0004-6361/201016028", language = "English", volume = "527", journal = "Astronomy and Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", number = "6", } . Astronomy and Astrophysics.

Observations of sausage modes in magnetic pores @article{60411e50af164614bd26c8330b6ac091, title = "Observations of sausage modes in magnetic pores", abstract = "We present here evidence for the observation of the magnetohydrodynamic (MHD) sausage modes in magnetic pores in the solar photosphere. Further evidence for the omnipresent nature of acoustic global modes is also found. The empirical decomposition method of wave analysis is used to identify the oscillations detected through a 4170 {\AA} {"}blue continuum{"} filter observed with the Rapid Oscillations in the Solar Atmosphere (ROSA) instrument. Out of phase, periodic behavior in pore size and intensity is used as an indicator of the presence of magnetoacoustic sausage oscillations. Multiple signatures of the magnetoacoustic sausage mode are found in a number of pores. The periods range from as short as 30 s up to 450 s. A number of the magnetoacoustic sausage mode oscillations found have periods of 3 and 5 minutes, similar to the acoustic global modes of the solar interior. It is proposed that these global oscillations could be the driver of the sausage-type magnetoacoustic MHD wave modes in pores.", keywords = "plasmas, Sun: photosphere, waves", author = "Richard Morton and Robert Erd{\'e}lyi and David Jess and Mihalis Mathioudakis", year = "2011", month = mar, doi = "10.1088/2041-8205/729/2/L18", language = "English", volume = "729", pages = "L18", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "2", } . The Astrophysical Journal.

Morton, R. J., Erdelyi, R., Jess, D. B., Mathioudakis, M.(2011). OBSERVATIONS OF SAUSAGE MODES IN MAGNETIC PORES . Astrophysical Journal Letters. 729. (2).

Morton, R.J., Erd&#233;lyi, R., Jess, D.B., Mathioudakis, M.(2011). Observations of sausage modes in magnetic pores . Astrophysical Journal Letters. 729. (2 PART II).

Morton, R. J., Ruderman, M. S.(2011). Kink and fluting modes of stratified coronal magnetic loops with elliptical cross-sections . Astronomy & Astrophysics. 527.

Morton, R.J., Ruderman, M.S.(2011). Kink and fluting modes of stratified coronal magnetic loops with elliptical cross-sections . Astronomy and Astrophysics. 527. (6).

Erdelyi, R., Al-Ghafri, K. S., Morton, R. J.(2011). Damping of Longitudinal Magneto-Acoustic Oscillations in Slowly Varying Coronal Plasma . Solar Physics. 272. (1). p. 73-89.

Morton, R.J., Ruderman, M.S., Erd&#233;lyi, R.(2011). Torsional Alfvén waves: Magneto-seismology in static and dynamic coronal plasmas . Astronomy and Astrophysics. 534.

Erd&#233;lyi, R., Al-Ghafri, K.S., Morton, R.J.(2011). Damping of Longitudinal Magneto-Acoustic Oscillations in Slowly Varying Coronal Plasma . Solar Physics. 272. (1). p. 73-89.

Morton, R. J., Ruderman, M. S., Erdelyi, R.(2011). Torsional Alfven waves: magneto-seismology in static and dynamic coronal plasmas . Astronomy & Astrophysics. 534.

Application of the theory of damping of kink oscillations by radiative cooling of coronal loop plasma @article{6d06b4daa12f47d39c973b086c3d27a9, title = "Application of the theory of damping of kink oscillations by radiative cooling of coronal loop plasma", abstract = "Aims. We present here a first comparative study between the observed damping of numerous fast kink oscillations and the theoretical model of their damping due to the cooling of coronal loops. The theory of damping of kink oscillations due to radiation of the solar plasma with a temporally varying background is applied here to all known cases of coronal kink oscillations. Methods. A recent dynamic model of cooling coronal loops predicts that transverse oscillations of such loops could be significantly damped due to the radiative cooling process (Morton \& Erd{\'e}lyi 2009, ApJ, 707, 750). The cooling of the loop plasma also has the consequence that the kink oscillation has a time-dependent frequency. The theory is applied to a relatively large number of known and reported examples of TRACE observations of damped kink oscillations. Results. We find that, for cooling timescales that are typical of EUV loops (500-2000 s), the observed damping of the transversal (i.e. kink) oscillations can be accounted for almost entirely by the cooling process in half of the examples. No other dissipative mechanism(s) seems to be needed to model the damping. In the remaining other examples, the cooling process does not appear to be able to account fully for the observed damping, though could still have a significant influence on the damping. In these cases another mechanism(s), e.g. resonant absorption, may be additionally required to account for the complete decay of oscillations. Also, we show that because of the dynamic nature of the background plasma, allowing for a time-dependent frequency provides a better fit profile for the data points of observations than a fit profile with a constant frequency, opening novel avenues for solar magneto-seismology.", keywords = "magnetohydrodynamics (MHD), plasmas, Sun: corona, waves", author = "Morton, \{R. J.\} and R. Erd{\'e}lyi", year = "2010", month = sep, day = "9", doi = "10.1051/0004-6361/201014504", language = "English", volume = "519", journal = "Astronomy and Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", number = "3", } . Astronomy and Astrophysics.

Propagating magneto-hydrodynamic waves in a cooling homogenous coronal plasma @article{c79e474e9bf94bd7a50b44fb20b095c7, title = "Propagating magneto-hydrodynamic waves in a cooling homogenous coronal plasma", abstract = "Aims: We present an investigation into how the cooling of the background plasma influences the propagation of slow and fast MHD wave modes supported by an unbounded, homogenous plasma. Previous investigations have suggested that the cooling of the plasma and a reduction in density could lead to the damping of fast magneto-acoustic oscillations. We aim to investigate whether cooling of the background plasma at a constant density may be responsible for the damping of slow and fast modes. Methods: The plasma is assumed homogeneous and the background temperature (pressure) is decreasing with time. The temperature change is assumed to be due to optically thin radiation. A special case of the radiative function is chosen to allow an analytical assessment of the effects of cooling on magneto-acoustic MHD modes and ensures the temperature evolution of the background plasma due to this radiation also matches the observed cooling profile of coronal loops. Results: A time-dependent dispersion relation is obtained on the slow timescale of cooling and full time-dependent solutions are found. Leading order equations for the amplitude of the waves are obtained and solved analytically for the slow and fast MHD modes. The cooling of the plasma is found to cause the frequency of the magneto-acoustic modes to decrease with time. The slow modes are found to experience a greater change in frequency than the fast modes. More importantly, the radiative losses also provide a significant damping of the slow mode and a small damping of the component of the fast mode perpendicular to the magnetic field. The damping of the slow mode is found to be strong within typical lifetimes of oscillations observed in coronal structures. Cooling could have important consequences and needs to be assessed when trying to determine what mechanism is responsible for the observed damping of coronal oscillations.", keywords = "waves, magnetohydrodynamics (MHD), Sun: corona, Sun: oscillations, plasmas", author = "Richard Morton and Hood, \{Alan William\} and Robert Erd{\'e}lyi", year = "2010", month = mar, doi = "10.1051/0004-6361/200913365", language = "English", volume = "512", pages = "A23", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", } . Astronomy & Astrophysics.

Morton, R. J., Hood, A. W., Erdelyi, R.(2010). Propagating magneto-hydrodynamic waves in a cooling homogenous coronal plasma . Astronomy & Astrophysics. 512.

Morton, R.J., Hood, A.W., Erd&#233;lyi, R.(2010). Propagating magneto-hydrodynamic waves in a cooling homogenous coronal plasma . Astronomy and Astrophysics. 512. (4).

Morton, R.J., Erd&#233;lyi, R.(2010). Application of the theory of damping of kink oscillations by radiative cooling of coronal loop plasma . Astronomy and Astrophysics. 519. (3).

Morton, R. J., Erdelyi, R.(2010). Application of the theory of damping of kink oscillations by radiative cooling of coronal loop plasma . Astronomy & Astrophysics. 519.

Transverse oscillations of a cooling coronal loop @article{baf50e90966741ada872148ea2784813, title = "Transverse oscillations of a cooling coronal loop", abstract = "Here we present an investigation into how cooling of the plasma influences the oscillation properties (e.g., eigenfunctions and eigenfrequencies) of transverse (i.e., kink) magnetohydrodynamic (MHD) waves in a compressible magnetic flux tube embedded in a gravitationally stratified and uniformly magnetized atmosphere. The cooling is introduced via a temperature-dependent density profile. A time-dependent governing equation is derived and an approximate zeroth-order solution is then obtained. From this the influence of cooling on the behavior of the eigenfrequencies and eigenfunctions of the transverse MHD waves is determined for representative cooling timescales. It is shown analytically, as the loop cools, how the amplitude of the perturbations is found to decrease as time increases. For cooling timescales of 900-2000 s (as observed in typical EUV loops), it is shown that the cooling has important and relevant influence on the damping times of loop oscillations. Next, the theory is put to the test. The damping due to cooling is fitted to a representative observation of standing kink oscillation of EUV loops. It is also shown with an explicit approximate analytical form, how the period of the fundamental and first harmonic of the kink mode changes with time as the loop cools. A consequence of this is that the value of the period ratio P 1/P 2, a tool that is popular in magneto-seismological studies in coronal diagnostics, decreases from the value of a uniform loop, 2, as the temperature decreases. The rate of change in P 1/P 2 is dependent upon the cooling timescale and is well within the observable range for typical EUV loops. Further to this, the magnitude of the anti-node shift of the eigenfunctions of the first harmonic is shown to continually increase as the loop cools, giving additional impetus to the use of spatial magneto-seismology of the solar atmosphere. Finally, we suggest that measurements of the rate of change in the eigenfunctions and eigenfrequencies of MHD oscillations can provide values for the cooling timescale and a further insight into the physics of coronal loops.", keywords = "MHD, plasmas, Sun: corona, waves", author = "Richard Morton and Robert Erd{\'e}lyi", year = "2009", month = dec, day = "10", doi = "10.1088/0004-637X/707/1/750", language = "English", volume = "707", pages = "750--760", journal = "The Astrophysical Journal", issn = "0004-637X", publisher = "American Astronomical Society", number = "1", } . The Astrophysical Journal.

The effect of elliptic shape on the period ratio P1/P2 of emerging coronal loops @article{7afede95dca946cc9f480f8b0586517b, title = "The effect of elliptic shape on the period ratio P1/P2 of emerging coronal loops", abstract = "Aims: We determine the effect of an elliptical shape on the period ratio for the standing transversal oscillations of a longitudinally stratified coronal loop throughout its emergence from the low solar atmosphere into the ubiquitously magnetised corona. Methods: Under the assumption that elliptical curvature has a negligible effect on eigenfrequencies, the equation that describes the projection of a density profile onto a magnetic flux tube with elliptical shape is obtained in a gravitationally stratified atmosphere. The effect of the elliptical shape on the period ratio of the fundamental mode to the first harmonic (P1/P2) at various stages of emergence is determined, assuming that the oscillation periods are much shorter than the characteristic time scale of loop emergence. Results: We find that there are two separate cases of elliptical shape that occur, the minor ellipse and the major ellipse. It is then shown how the period ratio P1/P2 is dependent upon the ellipticity (ɛ), the parameter characterising the stage of emergence (λ) and the density scale height (H). Ellipticity is found to make an important contribution to P1/P2 for the minor ellipse when compared to its counterpart of standing oscillations of stratified loops with semi-circle or circle-arc shape. The major ellipse was found to have a lesser effect on the period ratio of standing oscillations. We also find the value of P1/P2 is dependent upon the stage of emergence of the loop, where the greatest contribution from emergence to the ratio of P1/P2 is when the loop is almost fully emerged. The important implication for magneto-seismological interpretations of the observations of oscillating coronal loops is that measurements of ellipticity and stage of emergence should supplement observations of oscillation periods and should be considered when applying observed frequencies of the fundamental mode and first harmonic to determine the diagnostic properties of these oscillating loops, e.g. the density scale height or strength of magnetic field. Neglecting the determination of ellipticity and stage of emergence may result in a 35\% error in estimating density scale height.", author = "Richard Morton and Robert Erd{\'e}lyi", year = "2009", month = jul, doi = "10.1051/0004-6361/200811405", language = "English", volume = "502", pages = "315--323", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", number = "1", } . Astronomy & Astrophysics.

Erd&#233;lyi, R., Morton, R. J. (2009). Magnetohydrodynamic waves in a compressible magnetic flux tube with elliptical cross-section .

Magnetohydrodynamic waves in a compressible magnetic flux tube with elliptical cross-section @article{56f910c80bc94eb3bc3cdfcece4a5e8b, title = "Magnetohydrodynamic waves in a compressible magnetic flux tube with elliptical cross-section", abstract = "Aims. The propagation of magnetohydrodynamic (MHD) waves in a finite, compressible magnetic flux tube with an elliptical cross-section embedded in a magnetic environment is investigated. Methods. We present the derivation of the general dispersion relation of linear magneto-acoustic wave propagation for a compressible magnetic flux tube with elliptical cross-section in a plasma with finite beta. The wave modes of propagation for the n=0 (symmetric) sausage and n=1 (anti-symmetric) kink oscillations are then examined within the limit of the thin flux tube approximation. Results. It is shown that a compressible magnetic tube with elliptical cross-section supports slow and fast magneto-acoustic waves. In the thin tube approximation, the slow sausage mode and the slow and fast kink modes are found in analogue to a circular cross-section. However, the kink modes propagate with different phase speeds depending on whether the axial displacement takes place along the major or minor axis of the ellipse. This feature is present in both the slow and the fast bands, providing two infinite sets of slow kink modes and two infinite sets of fast kink modes, i.e. each corresponding cylindrical mode splits into two sets of modes due to the ellipticity. The difference between the phase speeds along the different axis is dependent on the ratio of the lengths of the two axes. Analytical expressions for the phase speeds are found. We show that the sausage modes do not split due to the introduced ellipticity and only the phase speed is modified when compared to the appropriate cylindrical counterpart. The percentage difference between the periods of the circular and elliptical cross-sections is also calculated, which reaches up to for oscillations along the major axis. The level of difference in period could be very important in magneto-seismological applications, when observed periods are inverted into diagnostic properties (e.g. magnetic field strength, gravitational scale height, tube expansion parameter). Also shown is the perturbation of focal points of the elliptical cross-section for different modes. It is found that the focal points are unperturbed for the sausage mode, but are perturbed for all higher modes.", author = "Richard Morton and Robert Erd{\'e}lyi", year = "2009", month = jan, doi = "10.1051/0004-6361:200810318", language = "English", volume = "494", pages = "295--309", journal = "Astronomy \& Astrophysics", issn = "0004-6361", publisher = "EDP Sciences", } . Astronomy & Astrophysics.

Erd&#233;lyi, R., Morton, R.J.(2009). Magnetohydrodynamic waves in a compressible magnetic flux tube with elliptical cross-section . Astronomy and Astrophysics. 494. (1). p. 295-309.

Erdelyi, R., Morton, R. J.(2009). Magnetohydrodynamic waves in a compressible magnetic flux tube with elliptical cross-section . Astronomy & Astrophysics. 494. (1). p. 295-309.

Morton, R. J., Erdelyi, R.(2009). The effect of elliptic shape on the period ratio P-1/P-2 of emerging coronal loops . Astronomy & Astrophysics. 502. (1). p. 315-323.

Morton, R.J., Erd&#233;lyi, R.(2009). The effect of elliptic shape on the period ratio P1/P2 of emerging coronal loops . Astronomy and Astrophysics. 502. (1). p. 315-323.

Morton, R. J., Erdelyi, R.(2009). TRANSVERSE OSCILLATIONS OF A COOLING CORONAL LOOP . Astrophysical Journal. 707. (1). p. 750-760.

Morton, R.J., Erd&#233;lyi, R.(2009). Transverse oscillations of a cooling coronal loop . Astrophysical Journal. 707. (1). p. 750-760.

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Richard Morton, Rahul Sharma (2025). Transverse energy injection scales at the base of the solar corona .

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Tiwari, S.K., Panesar, N.K., Moore, R.L., de Pontieu, B., Winebarger, A.R., Golub, L., Savage, S.L., Rachmeler, L.A., Kobayashi, K., Testa, P., et al.(2019). Fine-scale explosive energy release at sites of prospective magnetic flux cancellation in the core of the solar active region observed by Hi-C 2.1, IRIS and SDO . arXiv.

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