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Related papers: A parameter study for modeling MgII h and k emissi…

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Recent high-cadence flare campaigns by the Interface Region Imaging Spectrograph (IRIS) have offered new opportunities to study rapid processes characteristic of flare energy release, transport, and deposition. Here, we examine high-cadence…

Solar and Stellar Astrophysics · Physics 2025-04-16 Juraj Lörinčík , Vanessa Polito , Graham S. Kerr , Laura A. Hayes , Alexander J. B. Russell

With machine learning entering into the awareness of the heliophysics community, solar flare prediction has become a topic of increased interest. Although machine learning models have advanced with each successive publication, the input…

Solar and Stellar Astrophysics · Physics 2020-03-11 Brandon Panos , Lucia Kleint

We present results of non-LTE modeling of H-alpha 6563 A and Mg II k&h 2796 A and 2803 A lines. This modeling is important for interpretation of coordinated observations from the recently launched NASA's IRIS mission and from the New Solar…

Solar and Stellar Astrophysics · Physics 2014-12-02 Viacheslav M. Sadykov , Alexander G. Kosovichev

Previous estimates of the solar flare abundances of Si, S, Cl, Ar, and K from the RESIK X-ray crystal spectrometer on board the CORONAS-F spacecraft were made on the assumption of isothermal X-ray emission. We investigate the effect on…

Solar and Stellar Astrophysics · Physics 2015-06-19 B. Sylwester , J. Sylwester , K. J. H. Phillips , A. Kepa , T. Mrosek

The Interface Region Imaging Spectrograph(IRIS) with its high spatial and temporal resolution brings exceptional plasma diagnostics of solar chromospheric and coronal activity during magnetic reconnection. The aim of this work is to study…

Solar and Stellar Astrophysics · Physics 2021-01-20 Reetika Joshi , Brigitte Schmieder , Akiko Tei , Guillaume Aulanier , Juraj Lörinčík , Ramesh Chandra , Petr Heinzel

Context: Flux emergence in the solar atmosphere is a complex process that causes a release of magnetic energy as heat and acceleration of solar plasma at a variety of spatial scales. Methods: We analysed imaging spectropolarimetric data…

A rich spectrum of molecular hydrogen (H$_2$) emission lines is seen in sensitive observations from the far ultraviolet (FUV) channels of the Interface Region Imaging Spectrograph (IRIS) during flare activity in solar active region NOAA…

Solar and Stellar Astrophysics · Physics 2024-10-08 Sarah A. Jaeggli , Adrian N. Daw

The main aim of this submission is to investigate the effects of some parameters like wave number, shear velocity, magnetic field and temperature for the growth rate of the magnetized Kelvin-Helmholtz instability (KHI) with incessant…

Solar and Stellar Astrophysics · Physics 2019-08-14 Huseyin Cavus , G. A. Hoshoudy

The bulk of solar flare energy is deposited in the chromosphere. Flare ribbons and footpoints in the chromosphere therefore offer great diagnostic potential of flare energy release and transport processes. High quality observations from the…

Solar and Stellar Astrophysics · Physics 2023-10-12 Graham S. Kerr , Adam F. Kowalski , Joel C. Allred , Adrian N. Daw , Melissa R. Kane

We study chromospheric emission to understand the temperature stratification in the solar chromosphere. We observed the intensity profile of the CaIIH line in a quiet Sun region close to the disk center at the German Vacuum Tower Telescope.…

Astrophysics · Physics 2009-11-13 R. Rezaei , J. H. M. J. Bruls , W. Schmidt , C. Beck , W. Kalkofen , R. Schlichenmaier

Solar flares are 3D phenomenon but modelling a flare in 3D, including many of the important processes in the chromosphere, is a computational challenge. Accurately modelling the chromosphere is important, even if the transition region and…

Solar and Stellar Astrophysics · Physics 2020-09-02 Graham S. Kerr , Joel C. Allred , Vanessa Polito

We report on radiative hydrodynamic simulations of moderate and strong solar flares. The flares were simulated by calculating the atmospheric response to a beam of non-thermal electrons injected at the apex of a one-dimensional closed…

Astrophysics · Physics 2009-11-13 J. C. Allred , S. L. Hawley , W. P. Abbett , M. Carlsson

We investigate the properties of cold gas at $10^4~\rm K$ around star-forming galaxies at $z~\sim~1$ using Mg II spectra through radiative transfer modeling. We utilize a comprehensive dataset of 624 galaxies from the MAGG and MUDF…

Astrophysics of Galaxies · Physics 2025-08-28 Seok-Jun Chang , Rajeshwari Dutta , Max Gronke , Michele Fumagalli , Fabrizio Arrigoni Battaia , Matteo Fossati

Semi-empirical models of the solar atmosphere are used to study the radiative environment of any planet in our solar system. There is a need for reliable atomic data for neutral atoms and ions in the atmosphere to obtain improved calculated…

Solar and Stellar Astrophysics · Physics 2022-01-19 J. I. Peralta , M. C. Vieytes , A. M. P. Mendez , D. M. Mitnik

In this study we measure physical parameters of the same set of 155 M and X-class solar flares observed with AIA/SDO as analyzed in Paper I, by performing a {\sl differential emission measure (DEM)} analysis to determine the flare peak…

Solar and Stellar Astrophysics · Physics 2015-06-17 Markus J. Aschwanden , Toshifumi Shimizu

Context. The radiative losses in the solar chromosphere vary from 4~kW~m$^{-2}$ in the quiet Sun, to 20~kW~m$^{-2}$ in active regions. The mechanisms that transport non-thermal energy to and deposit it in the chromosphere are still not…

Solar and Stellar Astrophysics · Physics 2018-04-18 Jorrit Leenaarts , Jaime de la Cruz Rodríguez , Sanja Danilovic , Göran Scharmer , Mats Carlsson

Recent observations from the Interface Region Imaging Spectrograph (IRIS) appear to show impulsive brightenings in high temperature lines, which when combined with simultaneous ground based observations in H$\alpha$, appear co-spatial to…

Solar and Stellar Astrophysics · Physics 2017-02-08 A. Reid , M. Mathioudakis , A. Kowalski , J. G. Doyle , J. C. Allred

The Interface Region Imaging Spectrograph (IRIS) routinely observes the Si IV resonance lines. When analyzing observations of these lines it has typically been assumed they form under optically thin conditions. This is likely valid for the…

Solar and Stellar Astrophysics · Physics 2019-01-30 Graham S. Kerr , Mats Carlsson , Joel C. Allred , Peter R. Young , Adrian N. Daw

The asteroseismic and planetary studies, like all research related to stars, need precise and accurate stellar atmospheric parameters as input. We aim at deriving the effective temperature (Teff), the surface gravity (log g), the…

The hydrogen Lyman lines ( 91.2 nm < lambda < 121.6 nm) are significant contributors to the radiative losses of the solar chromosphere, and are enhanced during flares. We have shown previously that the Lyman lines observed by the Extreme…

Solar and Stellar Astrophysics · Physics 2018-08-08 Stephen A Brown , Lyndsay Fletcher , Graham S Kerr , Nicolas Labrosse , Adam F Kowalski , Jaime De La Cruz Rodríguez