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Loop-aligned hydrodynamic modelings help better understand the thermodynamic evolution of flaring plasma confined in solar flare loops. Conventional loop modelings typically assume a uniform loop cross section. With a variation of the cross…

Solar and Stellar Astrophysics · Physics 2026-02-24 Yu Dai , Shihan Li , Wenlong Tang , Zhen Li , Mingde Ding

Context. Transverse oscillations of coronal structures are currently intensively studied to explore the associated magnetohydrodynamic wave physics and perform seismology of the local medium. Aims. We make a first attempt to measure the…

Solar and Stellar Astrophysics · Physics 2020-07-01 C. R. Goddard , G. Nisticò

The standing slow magneto-acoustic oscillations in cooling coronal loops are investigated. There are two damping mechanisms which are considered to generate the standing acoustic modes in coronal magnetic loops namely thermal conduction and…

Solar and Stellar Astrophysics · Physics 2015-01-13 Khalil Salim Al-Ghafri

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 carry out a study of the global three-dimensional (3D) structure of the electron density and temperature of the quiescent inner solar corona ($r<1.25 R_\odot$) by means of tomographic reconstructions and magnetohydrodynamic simulations.…

Solar and Stellar Astrophysics · Physics 2020-06-17 D. G. Lloveras , A. M. Vásquez , F. A. Nuevo , C. Mac Cormack , N. Sachdeva , W. Manchester , B. Van der Holst , R. A. Frazin

Previous solar observations have shown that coronal loops near 1 MK are difficult to reconcile with simple heating models. These loops have lifetimes that are long relative to a radiative cooling time, suggesting quasi-steady heating. The…

Small (400 to 4000 km) and short lived (10 to 200 km) extreme ultraviolet (EUV) brightenings, detected by the High Resolution Imager EUV (HRIEUV), have been found to be ubiquitous in the Quiet Sun (QS). Their contribution to coronal heating…

Solar and Stellar Astrophysics · Physics 2025-07-02 A. Dolliou , J. A. Klimchuk , S. Parenti , K. Bocchialini

aims: We aim to provide an estimate of the minimum temperature of the quiet solar chromosphere. methods: We perform a 2D radiation-MHD simulation spanning the upper convection zone to the lower corona. The simulation includes non-LTE…

Solar and Stellar Astrophysics · Physics 2015-05-28 Jorrit Leenaarts , Mats Carlsson , Viggo Hansteen , Boris V. Gudiksen

We present a Differential Emission Measure (DEM) analysis of the quiet solar corona on disk using data obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on {\it Hinode}. We show that the expected quiet Sun DEM distribution can…

Solar and Stellar Astrophysics · Physics 2009-11-09 David H. Brooks , Harry P. Warren , David R. Williams , Tetsuya Watanabe

Broad differential emission measure (DEM) distributions in the corona are a sign of multi-thermal plasma along the line-of-sight. Traditionally, this is interpreted as evidence of multi-stranded loops. Recently, however, it has been shown…

Solar and Stellar Astrophysics · Physics 2018-12-05 Tom Van Doorsselaere , Patrick Antolin , Kostas Karampelas

We study the thermal structure and energetics of the point-like EUV brightenings within a system of fan loops observed in the active region \textsl{AR~11520}. These brightenings were simultaneously observed on 2012 July 11 by the…

Solar and Stellar Astrophysics · Physics 2018-07-18 Srividya Subramanian , Vinay L. Kashyap , Durgesh Tripathi , Maria S. Madjarska , J. G. Doyle

In coronal loop modeling, it is commonly assumed that the loops are semi-circular with a uniform cross-sectional area. However, observed loops are rarely semi-circular, and extrapolations of the magnetic field show that the field strength…

Solar and Stellar Astrophysics · Physics 2022-07-20 Jeffrey W. Reep , Ignacio Ugarte-Urra , Harry P. Warren , Will T. Barnes

We present a first systematic study on the cross-sectional temperature structure of coronal loops using the six coronal temperature filters of the Atmospheric Imaging Assembly (AIA) instrument on the Solar Dynamics Observatory (SDO). We…

Solar and Stellar Astrophysics · Physics 2015-05-27 Markus J. Aschwanden , Paul Boerner

A model interpreting variations of EUV brightness upward propagating in solar coronal loops as slow magnetoacoustic waves is developed. A loop is considered to have a non-zero plane inclination angle and offset of circular loop centre from…

Astrophysics · Physics 2009-11-07 D. Tsiklauri , V. M. Nakariakov

Using multi-wavelength observations from the Solar Dynamics Observatory (SDO), we investigated the six-month decay process of the solar active region NOAA AR 12738 from April to October 2019. We systematically analyzed the region's…

Solar and Stellar Astrophysics · Physics 2026-03-11 Jiasheng Wang , Yu Xu , Zhengyong Hou

The detailed knowledge of plasma heating and acceleration region properties presents a major observational challenge in solar flare physics. Using the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), the high temperature differential…

Solar and Stellar Astrophysics · Physics 2015-12-02 Natasha Jeffrey , Eduard Kontar , Brian Dennis

Magnetic loops are building blocks of the closed-field corona. While active region loops are readily seen in images taken at EUV and X-ray wavelengths, quiet Sun loops are seldom identifiable and therefore difficult to study on an…

Solar and Stellar Astrophysics · Physics 2015-06-05 Zhenguang Huang , Richard A. Frazin , Enrico Landi , Ward B. Manchester , Alberto M. Vásquez , Tamas I. Gombosi

It is extremely difficult to simulate the details of coronal heating and also make meaningful predictions of the emitted radiation. Thus, testing realistic models with observations is a major challenge. Observational signatures of coronal…

Solar and Stellar Astrophysics · Physics 2022-11-02 James A. Klimchuk , Kalman J. Knizhnik , Vadim M. Uritsky

The evolution of a coronal loop is studied by means of numerical simulations of the fully compressible three-dimensional magnetohydrodynamic equations using the HYPERION code. The footpoints of the loop magnetic field are advected by random…

Solar and Stellar Astrophysics · Physics 2016-01-22 R. B. Dahlburg , G. Einaudi , B. D. Taylor , I. Ugarte-Urra , H. P. Warren , A. F. Rappazzo , M. Velli

How the solar corona is heated to high temperatures remains an unsolved mystery in solar physics. In the present study we analyse observations of 50 whole active-region loops taken with the Extreme-ultraviolet Imaging Spectrometer (EIS) on…

Solar and Stellar Astrophysics · Physics 2017-06-28 Haixia Xie , Maria S. Madjarska , Bo Li , Zhenghua Huang , Lidong Xia , Thomas Wiegelmann , Hui Fu , Chaozhou Mou