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The scale heights of stratification and the widths of steady solar coronal loops exhibit properties unexplained by standard theory: observed scale heights are often much greater than static theory predicts, while the nearly-constant widths…

Astrophysics · Physics 2008-11-26 Gordon Petrie

The solar corona is much hotter than the photosphere and chromosphere, but the physical mechanism responsible for heating the coronal plasma remains unidentified yet. The thermal microwave emission, which is produced in strong magnetic…

Solar and Stellar Astrophysics · Physics 2025-08-27 Alexey A. Kuznetsov , Gregory D. Fleishman , Gelu M. Nita , Sergey A. Anfinogentov

Most 1d hydrodynamic models of plasma confined to magnetic flux tubes assume circular cross-section of these tubes. We use potential field models to show that flux tubes in circumstances relevant to the solar corona do not in general…

Solar and Stellar Astrophysics · Physics 2021-06-29 A. Malanushenko , C. J. Schrijver

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

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

We investigate a possibility of heating of the loops and other closed magnetic structures in active regions of the solar corona by the flow of solar wind (plus other flows that may be present) across the magnetic field lines (that are…

Astrophysics · Physics 2007-05-23 David Tsiklauri

Coronal loops are the building blocks of the X-ray bright solar corona. They owe their brightness to the dense confined plasma, and this review focuses on loops mostly as structures confining plasma. After a brief historical overview, the…

Solar and Stellar Astrophysics · Physics 2015-05-20 Fabio Reale

This work consists of two parts: the first devoted to the study of the heating of the magnetically confined Solar Corona, and the second to the acceleration of the Slow Solar Wind. Direct 3D reduced MHD simulations are presented. They model…

Solar and Stellar Astrophysics · Physics 2010-01-13 A. F. Rappazzo

One scenario proposed to explain the million degrees solar corona is a finely-stranded corona where each strand is heated by a rapid pulse. However, such fine structure has neither been resolved through direct imaging observations nor…

Solar and Stellar Astrophysics · Physics 2015-05-28 Fabio Reale , Massimiliano Guarrasi , Paola Testa , Edward E. DeLuca , Giovanni Peres , Leon Golub

It is widely believed that loops observed in the solar atmosphere trace out magnetic field lines. However, the degree to which magnetic field extrapolations yield field lines that actually do follow loops has yet to be studied…

Solar and Stellar Astrophysics · Physics 2018-06-27 Harry P. Warren , Nicholas A. Crump , Ignacio Ugarte-Urra , Xudong Sun , Markus J. Aschwanden , Thomas Wiegelmann

The structure of the solar corona is dominated by the magnetic field because the magnetic pressure is about four orders of magnitude higher than the plasma pressure. Due to the high conductivity the emitting coronal plasma (visible e.g. in…

Astrophysics · Physics 2009-06-25 T. Wiegelmann , B. Inhester , A. Lagg , S. K. Solanki

Observed spectral profiles of emission lines from the corona are found to have widths exceeding the thermal line width. To investigate the physical mechanism, we run a 3D MHD model of a single, straightened loop in which we partially…

Solar and Stellar Astrophysics · Physics 2024-04-02 C. A. Breu , H. Peter , S. K. Solanki , R. Cameron , I. De Moortel

The basic observational properties of "coronal partings" -- the special type of quasi-one-dimensional magnetic structures, identified by a comparison of the coronal X-ray and EUV images with solar magnetograms -- are investigated. They…

Space Physics · Physics 2016-01-27 Igor F. Nikulin , Yurii V. Dumin

A model for the solar coronal magnetic field is proposed where multiple directed loops evolve in space and time. Loops injected at small scales are anchored by footpoints of opposite polarity moving randomly on a surface. Nearby footpoints…

Statistical Mechanics · Physics 2009-11-07 D. Hughes , M. Paczuski , R. O. Dendy , P. Helander , K. G. McClements

Coronal loops, seen in solar coronal images, are believed to represent emission from magnetic flux tubes with compact cross-sections. We examine the 3D structure of plasma above an active region in a radiative magnetohydrodynamic simulation…

Solar and Stellar Astrophysics · Physics 2022-03-09 A. Malanushenko , M. C. M. Cheung , C. E. DeForest , J. A. Klimchuk , M. Rempel

Coronal loops interconnecting two active regions, called as interconnecting loops (ILs), are prominent large-scale structures in the solar atmosphere. They carry a significant amount of magnetic flux, therefore are considered to be an…

Solar and Stellar Astrophysics · Physics 2018-06-27 Guohui Du , Yao Chen , Chunming Zhu , Chang Liu , Lili Ge , Bing Wang , Chuanyang Li , Haimin Wang

One proposed resolution to the long-standing problem of solar coronal heating involves the buildup of magnetic energy in the corona due to turbulent motions at the photosphere that braid the coronal field, and the subsequent release of this…

Solar and Stellar Astrophysics · Physics 2015-05-27 D. I. Pontin , G. Hornig

The magnetic field in the Sun's corona stores energy that can be released to heat the coronal plasma and drive solar eruptions. Measurements of the global coronal magnetic field have been limited to a few snapshots. We present observations…

Solar and Stellar Astrophysics · Physics 2024-10-23 Zihao Yang , Hui Tian , Steven Tomczyk , Xianyu Liu , Sarah Gibson , Richard J. Morton , Cooper Downs

Quasi-periodic propagating disturbances in coronal structures have been interpreted as slow magneto-acoustic waves and/or periodic upflows. Here we aim to understand their nature from the observed properties using a three-hour imaging…

Solar and Stellar Astrophysics · Physics 2015-06-11 S. Krishna Prasad , D. Banerjee , T. Van Doorsselaere , J. Singh

The heating of coronal loops is investigated to understand the observational consequences in terms of the thermodynamics and radiative losses from the Sun as well as the magnetized coronae of stars with an outer convective envelope. The…

Solar and Stellar Astrophysics · Physics 2018-07-02 A. F. Rappazzo , R. B. Dahlburg , G. Einaudi , M. Velli