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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 evolution of the parameters that describe the non-thermal electron…

Solar and Stellar Astrophysics · Physics 2015-06-10 Michael B. Kennedy , Ryan O. Milligan , Joel C. Allred , Mihalis Mathioudakis , Francis P. Keenan

In order to understand the flare trigger mechanism, we conducted three-dimensional magnetohydrodynamic simulations using a coronal magnetic field model derived from data observed by the Hinode satellite. Several types of magnetic bipoles…

Solar and Stellar Astrophysics · Physics 2017-06-23 Johan Muhamad , Kanya Kusano , Satoshi Inoue , Daikou Shiota

Solar flares are driven by release of the free magnetic energy and its conversion to other forms of energy -- kinetic, thermal, and nonthermal. Quantification of partitions between these energy components and their evolution is needed to…

Solar and Stellar Astrophysics · Physics 2023-08-02 Gregory D. Fleishman , Gelu M. Nita , Galina G. Motorina

The discovery of hard X-ray sources near the top of a flaring loop by the HXT instrument on board the YOHKOH satellite represents a significant progress towards the understanding of the basic processes driving solar flares. In this paper we…

Astrophysics · Physics 2009-11-07 Vahe' Petrosian , Timothy Q. Donaghy , James M. McTiernan

Solar flares involve impulsive energy release, which results in enhanced radiation over a broad spectral range and a wide range of heights. In particular, line emission from the chromosphere can provide critical diagnostics of plasma…

Solar and Stellar Astrophysics · Physics 2015-06-23 Fatima Rubio da Costa , Lucia Kleint , Vahé Petrosian , Alberto Sainz Dalda , Wei Liu

We analyze a 96 ks Chandra/HETGS observation of the single G-type giant HR 9024. The high flux allows us to examine spectral line and continuum diagnostics at high temporal resolution, to derive plasma parameters. A time-dependent 1D…

Astrophysics · Physics 2011-02-11 Paola Testa , Fabio Reale , David Garcia-Alvarez , David P. Huenemoerder

A 1-D loop radiative hydrodynamic model that incorporates the effects of gravitational stratification, heat conduction, radiative losses, external heat input, presence of helium, and Braginskii viscosity is used to simulate elementary flare…

Astrophysics · Physics 2009-11-10 D. Tsiklauri , M. J. Aschwanden , V. M. Nakariakov , T. D. Arber

Recent simulations of solar active regions have shown that it is possible to reproduce both the total intensity and the general morphology of the high temperature emission observed at soft X-ray wavelengths using static heating models.…

Astrophysics · Physics 2011-02-11 Harry P. Warren , Amy R. Winebarger

The high densities, long lifetimes, and narrow emission measure distributions observed in coronal loops with apex temperatures near 1 MK are difficult to reconcile with physical models of the solar atmosphere. It has been proposed that the…

Solar and Stellar Astrophysics · Physics 2010-04-08 Harry P. Warren , David M. Kim , Amanda M. DeGiorgi , Ignacio Ugarte-Urra

Solar flares are an explosive phenomenon, where super-sonic flows and shocks are expected in and above the post-flare loops. To understand the dynamics of post-flare loops, a two-dimensional magnetohydrodynamic (2D MHD) simulation of a…

Solar and Stellar Astrophysics · Physics 2015-06-03 Shinsuke Takasao , Takuma Matsumoto , Naoki Nakamura , Kazunari Shibata

In this paper, we present the results of an analysis of 481 weak solar flares, from A0.01 to the B \textit{GOES} class, that were observed during the period of extremely low solar activity from 2009 April to July. For all flares we measured…

Solar and Stellar Astrophysics · Physics 2017-06-20 A. S. Kirichenko , S. A. Bogachev

Context. Multi-dimensional solar flare simulations have not yet included detailed analysis of the lower atmospheric responses such as down-flowing chromospheric compressions and chromospheric evaporation processes. Aims. We present an…

Solar and Stellar Astrophysics · Physics 2024-02-02 Malcolm Druett , Wenzhi Ruan , Rony Keppens

Solar flares are large-scale releases of energy in the solar atmosphere, which are characterised by rapid changes in the hydrodynamic properties of plasma from the photosphere to the corona. Solar physicists have typically attempted to…

Solar and Stellar Astrophysics · Physics 2012-06-26 S. Adamakis , C. L. Raftery , R. W. Walsh , P. T. Gallagher

Optical flares have been observed from magnetically active stars for many decades; unsurprisingly, the spectra and temporal evolution are complicated. For example, the shortcomings of optically thin, static slab models have long been…

Solar and Stellar Astrophysics · Physics 2024-07-23 Adam F. Kowalski , Joel C. Allred , Mats Carlsson

Coronal flare emission is commonly observed to decay on timescales longer than those predicted by impulsively-driven, one-dimensional flare loop models. This discrepancy is most apparent during the gradual phase, where emission from these…

Solar and Stellar Astrophysics · Physics 2023-03-01 William Ashfield , Dana Longcope

In previous works we have developed a method to convert solar X-ray data, collected with the Yohkoh/SXT, into templates of stellar coronal observations. Here we apply the method to several solar flares, for comparison with stellar X-ray…

Astrophysics · Physics 2009-11-06 F. Reale , G. Peres , S. Orlando

The interaction of a free-electron-laser pulse with a moderate or large size cluster is known to create a quasi-neutral nanoplasma, which then expands on hydrodynamic timescale, i.e., $>1$ ps. To have a better understanding of ion and…

Plasma Physics · Physics 2016-06-22 Vikrant Saxena , Zoltan Jurek , Beata Ziaja , Robin Santra

It is widely believed that magnetic flux ropes are the key structure of solar eruptions; however, their observable counterparts are not clear yet. We study a flare associated with flux rope eruption in a comprehensive radiative…

Solar and Stellar Astrophysics · Physics 2022-07-20 Can Wang , Feng Chen , Mingde Ding , Zekun Lu

Decimetric radio observations of the impulsive solar flare on October 5, 1992, 09:25 UT show a long series of quasi-periodic pulsations deeply modulating a continuum in the 0.6-2 GHz range that is slowly drifting toward lower frequencies.…

Astrophysics · Physics 2007-05-23 B. Kliem , M. Karlicky , A. O. Benz

Self-organization in continuous systems is associated with dissipative processes. In particular, for magnetized plasmas, it is known as magnetic relaxation, where the magnetic energy is converted into heat and kinetic energy of flow through…

Solar and Stellar Astrophysics · Physics 2024-01-23 Satyam Agarwal , Ramit Bhattacharyya , Shangbin Yang