Publications (46)
Temporal evolution of small-scale internetwork magnetic fields in the solar photosphere
Ryan J. Campbell, Mihalis Mathioudakis, Manuel Collados +5
While the longitudinal field that dominates photospheric network regions has been studied extensively, small scale transverse fields have recently been found to be ubiquitous in th…
Horizontal Magnetic Fields Dominate the Quiet Sun Internetwork in Sunrise III Observations. Evidence from Traditional and Transformer-Based Inversions
Ryan J. Campbell, Carlos Quintero Noda, Manuel Collados +41
The relative prevalence of horizontal and vertical magnetic fields in the quiet-Sun internetwork remains debated, owing to the weak linear polarisation signals that make the inferr…
Formation Of The Lyman Continuum During Solar Flares
Shaun A. McLaughlin, Ryan O. Milligan, Graham S. Kerr +3
The Lyman Continuum (LyC; Ã ) forms at the top of the chromosphere in the quiet-Sun, making LyC a powerful tool for probing the chromospheric plasma during solar flares. T…
Time-Dependent Density Diagnostics of Solar Flare Plasmas Using SDO/EVE
Ryan O. Milligan, Michael B. Kennedy, Mihalis Mathioudakis +1
Temporally-resolved electron density measurements of solar flare plasmas are presented using data from the EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory (…
The magnetic properties of photospheric magnetic bright points with high resolution spectropolarimetry
Peter H. Keys, Aaron Reid, Mihalis Mathioudakis +7
Magnetic bright points are small-scale magnetic elements ubiquitous across the solar disk, with the prevailing theory suggesting that they form due to the process of convective col…
The Radiated Energy Budget of Chromospheric Plasma in a Major Solar Flare Deduced From Multi-Wavelength Observations
Ryan O. Milligan, Graham S. Kerr, Brian R. Dennis +7
This paper presents measurements of the energy radiated by the lower solar atmosphere, at optical, UV, and EUV wavelengths, during an X-class solar flare (SOL2011-02-15T01:56) in r…
Identifying plasma fractionation processes in the chromosphere using IRIS
David M. Long, Deborah Baker, Andy S. H. To +7
The composition of the solar corona differs from that of the photosphere, with the plasma thought to fractionate in the solar chromosphere according to the First Ionisation Potenti…
On the 5-Minute Oscillations of Photospheric and Chromospheric Swirls
Jiajia Liu, David Jess, Robert Erdélyi +1
Swirls are ubiquitous in the solar atmosphere. They are believed to be related to the excitation of different modes of magnetohydrodynamic waves and pulses, as well as spicules. Ho…
Reproducing Type II White-Light Solar Flare Observations with Electron and Proton Beam Simulations
OndÅej Procházka, Aaron Reid, Ryan O. Milligan +3
We investigate the cause of the suppressed Balmer series and the origin of the white-light continuum emission in the X1.0 class solar flare on 2014 June 11. We use radiative hydrod…
Multi-wavelength observations of the 2014 June 11 M3.9 flare: temporal and spatial characteristics
Damian J. Christian, David Kuridze, David B. Jess +2
We present multi-wavelength observations of an M-class flare (M3.9) that occurred on 2014 June 11. Our observations were conducted with the Dunn Solar Telescope (DST), adaptive opt…
Chromospheric Velocities of a C-class Flare
Peter H. Keys, David B. Jess, Mihalis Mathioudakis +1
We use high spatial and temporal resolution observations from the Swedish Solar Telescope to study the chromospheric velocities of a C-class flare originating from active region NO…
Deconstructing Photospheric Spectral Lines in Solar and Stellar Flares
Aaron J. Monson, Mihalis Mathioudakis, Adam F. Kowalski
During solar flares, spectral lines formed in the photosphere have been shown to exhibit changes to their profiles despite the challenges of energy transfer to these depths. Recent…
Alfven Waves in the Solar Atmosphere
Mihalis Mathioudakis, David Jess, Robertus Erdelyi
Alfven waves are considered to be viable transporters of the non-thermal energy required to heat the Sun's quiescent atmosphere. An abundance of recent observations, from state-of-…
Exploring magnetic loops and serpentine fields in the quiet Sun with the GRIS-IFU
Ryan James Campbell, Ricardo Gafeira, Mihalis Mathioudakis +2
Synthetic observations produced from radiative magnetohydronamic simulations have predicted that higher polarization fractions in the quiet solar photosphere would be revealed by i…
The Influence of Magnetic Field on Oscillations in the Solar Chromosphere
D. Shaun Bloomfield, R. T. James McAteer, Mihalis Mathioudakis +1
Two sequences of solar images obtained by the Transition Region and Coronal Explorer in three UV passbands are studied using wavelet and Fourier analysis and compared to the photos…
Flare Induced Sunquake Signatures in the Ultraviolet as Observed by the Atmospheric Imaging Assembly
Sean Quinn, Mihalis Mathioudakis, Christopher J. Nelson +3
Sunquakes (SQs) have been routinely observed in the solar photosphere, but it is only recently that signatures of these events have been detected in the chromosphere. We investigat…
Solar Flare Impulsive Phase Emission Observed with SDO/EVE
Michael B. Kennedy, Ryan O. Milligan, Mihalis Mathioudakis +1
Differential emission measures (DEMs) during the impulsive phase of solar flares were constructed using observations from the EUV Variability Experiment (EVE) and the Markov-Chain…
The Evolution of K Blackbody-Like Continuum Radiation in the Impulsive Phase of dMe Flares
Adam F. Kowalski, Mihalis Mathioudakis, Suzanne L. Hawley
The near-ultraviolet and optical (white-light) continuum radiation in M dwarf flares exhibits a range of observed characteristics, suggesting that the amount of heating at large op…
The F-CHROMA grid of 1D RADYN flare models
Mats Carlsson, Lyndsay Fletcher, Joel Allred +6
Context: Solar flares are the result of the sudden release of magnetic energy in the corona. Much of this energy goes into accelerating charged particles to high velocity. These pa…
Hydrogen Emission in Type II White-light Solar Flares
OndÅej Procházka, Aaron Reid, Mihalis Mathioudakis
Type II WLFs have weak Balmer line emission and no Balmer jump. We carried out a set of radiative hydrodynamic simulations to understand how the hydrogen radiative losses vary with…
Chromospheric Bubbles in Solar Flares
Aaron Reid, Bogdan Zhigulin, Mats Carlsson +1
We analyze a grid of radiative hydrodynamic simulations of solar flares to study the energy balance and response of the atmosphere to nonthermal electron beam heating. The appearan…
Photospheric observations of surface and body modes in solar magnetic pores
Peter H. Keys, Richard J. Morton, David B. Jess +8
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…
Small-scale bright point characteristics at high-resolution with the Daniel K. Inouye Solar Telescope
Peter H. Keys, Ryan J. Campbell, Dylan K. J. Magill +9
Bright points (BPs) are small-scale, dynamic features that are ubiquitous across the solar disc and are often associated with the underlying magnetic field. Using broadband photosp…
The Chromospheric Response to the Sunquake generated by the X9.3 Flare of NOAA 12673
Sean Quinn, Aaron Reid, Mihalis Mathioudakis +3
Active region NOAA 12673 was extremely volatile in 2017 September, producing many solar flares, including the largest of solar cycle 24, an X9.3 flare of 06 September 2017. It has…
Dynamic properties of bright points in an active region
Peter H. Keys, Mihalis Mathioudakis, David B. Jess +2
Context. Bright points (BPs) are small-scale, magnetic features ubiquitous across the solar surface. Previously, we have observed and noted their properties for quiet Sun regions.…
Continuum enhancements, line profiles and magnetic field evolution during consecutive flares
Francesca Zuccarello, Salvo L. Guglielmino, Vincenzo Capparelli +5
During solar flares, magnetic energy can be converted into electromagnetic radiation from radio waves to rays. Enhancements in the continuum at visible wavelengths give rise t…
Non-thermal distributions and energy transport in the solar flares
Sarah Matthews, Guilio del Zanna, Ariadna Calcines +9
Determining the energy transport mechanisms in flares remains a central goal in solar flares physics that is still not adequately answered by the 'standard flare model'. In particu…
Observational Evidence for Gentle Chromospheric Evaporation During the Impulsive Phase of a Solar Flare
Ryan O. Milligan, Peter T. Gallagher, Mihalis Mathioudakis +1
Observational evidence for gentle chromospheric evaporation during the impulsive phase of a C9.1 solar flare is presented using data from the Reuven Ramaty High-Energy Solar Spectr…
Radiative hydrodynamic modelling and observations of the X-class solar flare on 2011 March 9
Michael B. Kennedy, Ryan O. Milligan, Joel C. Allred +2
We investigated the response of the solar atmosphere to non-thermal electron beam heating using the radiative transfer and hydrodynamics modelling code RADYN. The temporal evolutio…
Science Requirement Document (SRD) for the European Solar Telescope (EST) (3rd Edition, December 2025)
Rolf Schlichenmaier, Luis R. Bellot Rubio, Manuel Collados Vera +31
The European Strategy Forum on Research Infrastructures (ESFRI) included the European Solar Telescope (EST) as an ESFRI Project in its 2016 Roadmap and confirmed this status in 202…
High-resolution spectropolarimetric observations of the temporal evolution of magnetic fields in photospheric bright points
Peter H. Keys, Aaron Reid, Mihalis Mathioudakis +7
Context. Magnetic bright points (MBPs) are dynamic, small-scale magnetic elements often found with field strengths of the order of a kilogauss within intergranular lanes in the pho…
Suppression of Hydrogen Emission in an X-class White-light Solar Flare
OndÅej Procházka, Ryan O. Milligan, Joel C. Allred +3
We present unique NUV observations of a well-observed X-class flare from NOAA 12087 obtained at OndÅejov Observatory. The flare shows a strong white-light continuum but no detecta…
Statistical Signatures of Nanoflare Activity. I. Monte Carlo Simulations and Parameter-space Exploration
David B. Jess, Chris J. Dillon, Michael S. Kirk +7
Small-scale magnetic reconnection processes, in the form of nanoflares, have become increasingly hypothesized as important mechanisms for the heating of the solar atmosphere, for d…
Power-law energy distributions of small-scale impulsive events on the active Sun: Results from IRIS
Nived Vilangot Nhalil, Chris J. Nelson, Mihalis Mathioudakis +2
Numerous studies have analysed inferred power-law distributions between frequency and energy of impulsive events in the outer solar atmosphere in an attempt to understand the predo…
M Dwarf Flare Continuum Variations on One-Second Timescales: Calibrating and Modeling of ULTRACAM Flare Color Indices
Adam F. Kowalski, Mihalis Mathioudakis, Suzanne L. Hawley +5
We present a large dataset of high cadence dMe flare light curves obtained with custom continuum filters on the triple-beam, high-speed camera system ULTRACAM. The measurements pro…
H and EUV observations of a partial CME
Damian J. Christian, David B. Jess, Patrick Antolin +1
We have obtained H high spatial and time resolution observations of the upper solar chromosphere and supplemented these with multi-wavelength observations from the Solar Dynami…
Application of Deep Learning to the Classification of Stokes Profiles: From the Quiet Sun to Sunspots
Ryan James Campbell, Mihalis Mathioudakis, Carlos Quintero Noda +2
The morphology of circular polarisation profiles from solar spectropolarimetric observations encode information about the magnetic field strength, inclination, and line-of-sight ve…
Umbral chromospheric fine structure and umbral flashes modelled as one: the corrugated umbra
Vasco M. J. Henriques, Chris J. Nelson, Luc H. M. Rouppe van der Voort +1
Small-scale umbral brightenings (SSUBs), umbral microjets, spikes or short dynamic fibrils (SDFs), and umbral dark fibrils are found in any observation of the chromosphere with suf…
H and H emission in a C3.3 solar flare: comparison between observations and simulations
Vincenzo Capparelli, Francesca Zuccarello, Paolo Romano +7
The Hydrogen Balmer series is a basic radiative loss channel from the flaring solar chromosphere. We report here on the analysis of an extremely rare set of simultaneous observatio…
Flare Induced Photospheric Velocity Diagnostics
Aaron J. Monson, Mihalis Mathioudakis, Aaron Reid +2
We present radiative hydrodynamic simulations of solar flares generated by the RADYN and RH codes to study the perturbations induced in photospheric Fe I lines by electron beam hea…
The Velocity Distribution of Solar Photospheric Magnetic Bright Points
Peter H. Keys, Mihalis Mathioudakis, David B. Jess +4
We use high spatial resolution observations and numerical simulations to study the velocity distribution of solar photospheric magnetic bright points. The observations were obtaine…
White Light Flare Continuum Observations with ULTRACAM
Adam F. Kowalski, Mihalis Mathioudakis, Suzanne L. Hawley +4
We present sub-second, continuous-coverage photometry of three flares on the dM3.5e star, EQ Peg A, using custom continuum filters with WHT/ULTRACAM. These data provide a new view…
The Search for Super-saturation in Chromospheric Emission
Damian J. Christian, Mihalis Mathioudakis, Tersi Arias +2
We investigate if the super-saturation phenomenon observed at X-ray wavelengths for the corona, exists in the chromosphere for rapidly rotating late-type stars. Moderate resolution…
Transformers for Stratified Spectropolarimetric Inversion: Proof of Concept
Ryan James Campbell, Mihalis Mathioudakis, Carlos Quintero Noda
Solar spectropolarimetric inversion -- inferring atmospheric conditions from the Stokes vector -- is a key diagnostic tool for understanding solar magnetism, but traditional invers…
Observations of Enhanced EUV Continua During An X-Class Solar Flare Using SDO/EVE
Ryan O. Milligan, Phillip C. Chamberlin, Hugh S. Hudson +5
Observations of extreme-ultraviolet (EUV) emission from an X-class solar flare that occurred on 2011 February 15 at 01:44 UT are presented, obtained using the EUV Variability Exper…
Expanding magnetic canopy structure and parasitic polarities in a quiet-Sun network element observed by Sunrise III/SCIP
Ryan J. Campbell, Carlos Quintero Noda, Mihalis Mathioudakis +44
We present high-resolution multi-line spectropolarimetric observations of a quiet-Sun network element obtained with the {\sc Sunrise~iii} Chromospheric Infrared SpectroPolarimeter.…