Publications (40)
Constraining the magnetic vector in the quiet solar photosphere and the impact of instrumental degradation
R. J. Campbell, S. Shelyag, C. Quintero Noda +3
With the advent of next generation high resolution telescopes, our understanding of how the magnetic field is organized in the internetwork (IN) photosphere is likely to advance.We…
Mesogranular structure in a hydrodynamical simulation
Å. Matloch, R. Cameron, S. Shelyag +2
We analyse mesogranular flow patterns in a three-dimensional hydrodynamical simulation of solar surface convection in order to determine its characteristics. We calculate divergenc…
Spectropolarimetrically accurate magnetohydrostatic sunspot model for forward modelling in helioseismology
D. Przybylski, S. Shelyag, P. S. Cally
We present a technique to construct a spectropolarimetrically accurate magneto-hydrostatic model of a large-scale solar magnetic field concentration, mimicking a sunspot. Using the…
Stellar Surface Magneto-Convection as a Source of Astrophysical Noise. I. Multi-component Parameterisation of Absorption Line Profiles
H. M. Cegla, S. Shelyag, C. A. Watson +1
We outline our techniques to characterise photospheric granulation as an astrophysical noise source. A four component parameterisation of granulation is developed that can be used…
Propagating Wave Phenomena Detected in Observations and Simulations of the Lower Solar Atmosphere
D. B. Jess, S. Shelyag, M. Mathioudakis +3
We present high-cadence observations and simulations of the solar photosphere, obtained using the Rapid Oscillations in the Solar Atmosphere imaging system and the MuRAM magneto-hy…
Stellar jitter from variable gravitational redshift: implications for RV confirmation of habitable exoplanets
H. M. Cegla, C. A. Watson, T. R. Marsh +6
A variation of gravitational redshift, arising from stellar radius fluctuations, will introduce astrophysical noise into radial velocity measurements by shifting the centroid of th…
Vortices in the solar photosphere
S. Shelyag, V. Fedun, R. Erdélyi +2
Using numerical simulations of the magnetised solar photosphere and radiative diagnostics of the simulated photospheric models, we further analyse the physical nature of magnetic p…
Signatures of quiet Sun reconnection events in Ca~{\sc ii}, H and Fe~{\sc i}
J. Shetye, S. Shelyag, A. L. Reid +3
We use observations of quiet Sun (QS) regions in the H 6563 Ã , Ca~{\sc ii} 8542 Ã \, and Fe~{\sc i} 6302 Ã lines. We observe brightenings in the wings of the H and Ca~{\sc…
Alfvén Wave Heating of the Solar Chromosphere: 1.5D models
T. D. Arber, C. S. Brady, S. Shelyag
Physical processes which may lead to solar chromospheric heating are analyzed using high-resolution 1.5D non-ideal MHD modelling. We demonstrate that it is possible to heat the chr…
Photospheric high-frequency acoustic power excess in sunspot umbra: signature of magneto-acoustic modes
S. Zharkov, S. Shelyag, V. Fedun +2
We present observational evidence for the presence of MHD waves in the solar photosphere deduced from SOHO/MDI Dopplergram velocity observations. The magneto-acoustic perturbations…
Evidence for the photospheric excitation of incompressible chromospheric waves
R. J. Morton, G. Verth, V. Fedun +2
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 connect…
Directional Time-Distance Probing of Model Sunspot Atmospheres
H. Moradi, P. S. Cally, D. Przybylski +1
A crucial feature not widely accounted for in local helioseismology is that surface magnetic regions actually open a window from the interior into the solar atmosphere, and that th…
Plasma properties and Stokes profiles during the lifetime of a photospheric magnetic bright point
R. L. Hewitt, S. Shelyag, M. Mathioudakis +1
Aims: to investigate the evolution of plasma properties and Stokes parameters in photospheric magnetic bright points using 3D magneto-hydrodynamical simulations and radiative diagn…
Ellerman Bombs with Jets: Cause and Effect
A. Reid, M. Mathioudakis, E. Scullion +3
Ellerman Bombs (EBs) are thought to arise as a result of photospheric magnetic reconnection. We use data from the Swedish 1-m Solar Telescope (SST), to study EB events on the solar…
Acoustic wave propagation in the solar sub-photosphere with localised magnetic field concentration: effect of magnetic tension
S. Shelyag, S. Zharkov, V. Fedun +2
Aims. In this paper we analyse numerically the propagation and dispersion of acoustic waves in the solar-like sub-photosphere with localised non-uniform magnetic field concentratio…
Stokes diagnostics of simulated solar magneto-convection
S. Shelyag, M. Schuessler, S. K. Solanki +1
We present results of synthetic spectro-polarimetric diagnostics of radiative MHD simulations of solar surface convection with magnetic fields. Stokes profiles of Zeeman-sensitive…
Global Stability and Periodicity in a Glucose-Insulin Regulation Model with a Single Delay
M. Angelova, G. Beliakov, A. Ivanov +1
A two-dimensional system of differential equations with delay modelling the glucose-insulin interaction processes in the human body is considered. Sufficient conditions are derived…
Analysis of 3D plasma motions in a chromospheric jet formed due to magnetic reconnection
J. J. González-Avilés, F. S. Guzmán, V. Fedun +4
Within the framework of resistive MHD, implementing the C7 equilibrium atmosphere model and a 3D potential magnetic field realistic configuration, we simulate the formation of a pl…
Spectro-polarimetric simulations of the solar limb: absorption-emission FeI and line profiles and torsional flows in the intergranular magnetic flux concentrations
S. Shelyag
Using radiative magneto-hydrodynamic simulations of the magnetised solar photosphere and detailed spectro-polarimetric diagnostics with the FeI and $6302.5\mathrm…
Centre-to-limb spectro-polarimetric diagnostics of simulated solar photospheric magneto-convection: signatures of photospheric Alfven waves
S. Shelyag, D. Przybylski
Using numerical simulations of the magnetised solar photosphere carried out with the radiative magneto-hydrodynamic code, MURaM, and detailed spectro-polarimetric diagnostics of th…
Tracking Magnetic Bright Point Motions Through the Solar Atmosphere
P. H. Keys, M. Mathioudakis, D. B. Jess +3
High cadence, multi-wavelength observations and simulations are employed for the analysis of solar photospheric magnetic bright points (MBPs) in the quiet Sun. The observations wer…
I. Jet Formation and Evolution due to 3D Magnetic Reconnection
J. J. González-Avilés, F. S. Guzmán, V. Fedun +3
Using simulated data-driven three-dimensional resistive MHD simulations of the solar atmosphere, we show that magnetic reconnection can be responsible of the formation of jets with…
Understanding Astrophysical Noise from Stellar Surface Magneto-Convection
H. M. Cegla, C. A. Watson, S. Shelyag +1
To obtain cm/s precision, stellar surface magneto-convection must be disentangled from observed radial velocities (RVs). In order to understand and remove the convective signature,…
Analysis of unresolved photospheric magnetic field structure using Fe I 6301 and 6302 lines
M. Gordovskyy., S. Shelyag, P. K. Browning +1
Early magnetographic observations indicated that magnetic field in the solar photosphere has unresolved small-scale structure. Near-infrared and optical data with extremely high sp…
Small-scale Hα Jets in the Solar Chromosphere
D. Kuridze, M. Mathioudakis, D. B. Jess +4
High temporal and spatial resolution observations from the Rapid Oscillations in the Solar Atmosphere (ROSA) multiwavelength imager on the Dunn Solar Telescope are used to study th…
A photospheric bright point model
S. Shelyag, M. Mathioudakis, F. P. Keenan +1
A magneto-hydrostatic model is constructed with spectropolarimetric properties close to those of solar photospheric magnetic bright points. Results of solar radiative magneto-conve…
Modelling the Rossiter-McLaughlin Effect: Impact of the Convective Centre-to-Limb Variations in the Stellar Photosphere
H. M. Cegla, M. Oshagh, C. A. Watson +3
Observations of the Rossiter-McLaughlin (RM) effect provide information on star-planet alignments, which can inform planetary migration and evolution theories. Here, we go beyond t…
Stellar Surface Magneto-Convection as a Source of Astrophysical Noise II. Center-to-Limb Parameterisation of Absorption Line Profiles and Comparison to Observations
H. M. Cegla, C. A. Watson, S. Shelyag +6
Manifestations of stellar activity (such as star-spots, plage/faculae, and convective flows) are well known to induce spectroscopic signals often referred to as astrophysical noise…
Ellerman Bombs - Evidence for Magnetic Reconnection in the Lower Solar Atmosphere
C. J. Nelson, S. Shelyag, M. Mathioudakis +4
The presence of photospheric magnetic reconnection has long been thought to give rise to short and impulsive events, such as Ellerman bombs (EBs) and Type II spicules. In this arti…
Periodic patterns in simple biological differential delay models
A. Ivanov, S. Shelyag
Periodic patterns in dynamical behaviours of biological models described by simple form differential delay equations are studied. Mathematical models are given by a class of scalar…
Using the Stokes V widths of Fe I lines for diagnostics of the intrinsic solar photospheric magnetic field
M. Gordovskyy, S. Shelyag, P. K. Browning +1
The goal of this study is to explore a novel method for the solar photospheric magnetic field diagnostics using Stokes V widths of different magnetosensitive Fe~I spectral lines. W…
Stellar Surface Magneto-Convection as a Source of Astrophysical Noise III. Sun-as-a-star Simulations and Optimal Noise Diagnostics
H. M. Cegla, C. A. Watson, S. Shelyag +2
Stellar surface magnetoconvection (granulation) creates asymmetries in the observed stellar absorption lines that can subsequently manifest themselves as spurious radial velocities…
Heating of the partially ionized solar chromosphere by waves in magnetic structures
S. Shelyag, E. Khomenko, A. de Vicente +1
In this paper, we show a "proof of concept" of the heating mechanism of the solar chromosphere due to wave dissipation caused by the effects of partial ionization. Numerical modeli…
Mechanisms for MHD Poynting flux generation in simulations of solar photospheric magneto-convection
S. Shelyag, M. Mathioudakis, F. P. Keenan
We investigate the generation mechanisms of MHD Poynting flux in the magnetised solar photosphere. Using radiative MHD modelling of the solar photosphere with initial magnetic conf…
Forward modelling of sub-photospheric flows for time-distance helioseismology
S. Shelyag, R. Erdelyi, M. J. Thompson
Results of forward modelling of acoustic wave propagation in a realistic solar sub-photosphere with two cases of steady horizontal flows are presented and analysed by the means of…
The Dynamics of Rapid Redshifted and Blueshifted Excursions in the Solar Halpha line
D. Kuridze, V. Henriques, M. Mathioudakis +5
We analyse high temporal and spatial resolution time-series of spectral scans of the Halpha line obtained with the CRisp Imaging SpectroPolarimeter (CRISP) instrument mounted on th…
Flows and magnetic field structures in reconnection regions of simulations of the solar atmosphere: do flux pile-up models work?
S. Shelyag, Y. E. Litvinenko, V. Fedun +3
We study the process of magnetic field annihilation and reconnection in simulations of magnetised solar photosphere and chromosphere with magnetic fields of opposite polarities and…
The Area Distribution of Solar Magnetic Bright Points
P. J. Crockett, M. Mathioudakis, D. B. Jess +3
Magnetic Bright Points (MBPs) are among the smallest observable objects on the solar photosphere. A combination of G-band observations and numerical simulations is used to determin…
Vorticity in the solar photosphere
S. Shelyag, P. Keys, M. Mathioudakis +1
Aims. We use magnetic and non-magnetic 3D numerical simulations of solar granulation and G-band radiative diagnostics from the resulting models to analyse the generation of small-s…
Alfvén waves in simulations of solar photospheric vortices
S. Shelyag, P. S. Cally, A. Reid +1
Using advanced numerical magneto-hydrodynamic simulations of the magnetised solar photosphere, including non-grey radiative transport and a non-ideal equation of state, we analyse…