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Coronal implosions - the convergence motion of plasmas and entrained magnetic field in the corona due to a reduction in magnetic pressure - can help to locate and track sites of magnetic energy release or redistribution during solar flares…

Solar and Stellar Astrophysics · Physics 2017-01-06 Juntao Wang , P. J. A. Simoes , L. Fletcher , J. K. Thalmann , H. S. Hudson , I. G. Hannah

Coronal supra-arcade downflows (SADs) are observed as dark trails descending towards hot turbulent fan shaped regions. Due to the large temperature values, and gradients in these fan regions the thermal conduction should be very efficient.…

Solar and Stellar Astrophysics · Physics 2020-04-22 E. Zurbriggen , A. Costa , A. Esquivel , M. Schneiter , M. Cécere

The corona of the Sun is dominated by emission from loop-like structures. When observed in X-ray or extreme ultraviolet emission, these million K hot coronal loops show a more or less constant cross section. In this study we show how the…

Solar and Stellar Astrophysics · Physics 2015-06-11 H. Peter , S. Bingert

We perform MHD modeling of a single bright coronal loop to include the interaction with a non-uniform magnetic field. The field is stressed by random footpoint rotation in the central region and its energy is dissipated into heating by…

Solar and Stellar Astrophysics · Physics 2016-10-12 F. Reale , S. Orlando , M. Guarrasi , A. Mignone , G. Peres , A. W. Hood , E. R. Priest

We present a series of numerical simulations aimed at understanding the nature and origin of turbulence in coronal loops in the framework of the Parker model for coronal heating. A coronal loop is studied via reduced magnetohydrodynamics…

Solar and Stellar Astrophysics · Physics 2015-03-13 A. F. Rappazzo , M. Velli , G. Einaudi

A significant impediment to solving the coronal heating problem is that we currently only observe active region (AR) loops in their cooling phase. Previous studies showed that the evolution of cooling loop densities and apex temperatures…

Solar and Stellar Astrophysics · Physics 2024-01-10 David H. Brooks , Jeffrey W. Reep , Ignacio Ugarte-Urra , John E. Unverferth , Harry P. Warren

This study investigates Parker instability in an interstellar medium (ISM) near the Galactic plane using three-dimensional magneto-hydrodynamic simulations. Parker instability arises from the presence of a magnetic field in a plasma,…

High Energy Astrophysical Phenomena · Physics 2011-01-06 Ying-Yi Lo , Chung-Ming Ko , Chih-Yueh Wang

There is considerable observational evidence of implosion of magnetic loop systems inside solar coronal active regions following high energy events like solar flares. In this work, we propose that such collapse can be modeled in three…

Solar and Stellar Astrophysics · Physics 2017-12-27 Aveek Sarkar , Bhargav Vaidya , Soumitra Hazra , Jishnu Bhattacharyya

A hot corona is suggested to be above the standard thin disk. The anisotropy of hard X-ray emission in radio-quiet active galactic nuclei implies that the corona is not static and probably moves outwards like winds. We perform…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Xiao-Hong Yang , De-Fu Bu , Qi-Xiu Li

Observations and simulations of coronal rain show that as cold and dense plasma falls through the corona it initially undergoes acceleration by gravity before the downward velocity saturates. Simulations have shown the emergence of an…

Solar and Stellar Astrophysics · Physics 2025-04-30 Andrew Hillier , Ramon Oliver , David Martínez-Gómez

We performed magnetohydrodynamic simulation of coronal mass ejections (CMEs) and associated giant arcade formations, and the results suggested new interpretations of observations of CMEs. We performed two cases of the simulation: with and…

We study a 2D cellular automaton (CA) model for the evolution of coronal loop plasmas. The model is based on the idea that coronal loops are made of elementary magnetic strands that are tangled and stressed by the displacement of their…

Solar and Stellar Astrophysics · Physics 2017-03-22 Marcelo López Fuentes , James A. Klimchuk

The relationship between a decaying strong turbulence and kinetic instabilities in a slowly expanding plasma is investigated using two-dimensional (2-D) hybrid expanding box simulations. We impose an initial ambient magnetic field…

We present in this Letter the first global comparison between traditional line-tied steady state magnetohydrodynamic models and a new, fully time-dependent thermodynamic magnetohydrodynamic simulation of the global corona. The maps are…

Solar and Stellar Astrophysics · Physics 2023-06-22 Emily I. Mason , Roberto Lionello , Cooper Downs , Jon A. Linker , Ronald M. Caplan

Solar coronal loops are commonly subject to oscillations. Observations of coronal oscillations are used to infer physical properties of the coronal plasma using coronal seismology. Excitation and evolution of oscillations in coronal loops…

Solar and Stellar Astrophysics · Physics 2021-03-17 P. Kohutova , A. Popovas

Coronal rain clumps and prominence knots are dense condensations with chromospheric to transition region temperatures that fall down in the much hotter corona. Their typical speeds are in the range 30--150~km~s$^{-1}$ and of the order of…

Solar and Stellar Astrophysics · Physics 2016-02-18 R. Oliver , R. Soler , J. Terradas , T. V. Zaqarashvili

We conducted a high-resolution numerical simulation of the solar corona above a stable active region. The aim is to test the field-line braiding mechanism for a sufficient coronal energy input. We also check the applicability of scaling…

Solar and Stellar Astrophysics · Physics 2018-05-17 Philippe-A. Bourdin , Sven Bingert , Hardi Peter

The measured average velocities in solar and stellar spectral lines formed at transition region temperatures have been difficult to interpret. However, realistic three-dimensional radiation magnetohydrodynamics (3D rMHD) models of the solar…

Solar and Stellar Astrophysics · Physics 2018-07-11 P. Zacharias , V. H. Hansteen , J. Leenaarts , M. Carlsson , B. V. Gudiksen

The coronal magnetic field evolution of 20 bipolar active regions (ARs) is simulated from their emergence to decay using the time-dependent nonlinear force-free field method of Mackay et al. A time sequence of cleaned photospheric…

Solar and Stellar Astrophysics · Physics 2021-01-13 Stephanie L. Yardley , Duncan H. Mackay , Lucie M. Green

The core collapse events observed in a stellarator experiment are studied by a three-dimensional nonlinear MHD simulations. In the low magnetic shear configuration like the Wendelstein 7-X, the rotational transform profile is very sensitive…

Plasma Physics · Physics 2021-12-08 Yasuhiro Suzuki , Shimpei Futatani , Joachim Geiger