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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

Despite decades of studying the Sun, the coronal heating problem remains unsolved. One fundamental issue is that we do not know the spatial scale of the coronal heating mechanism. At a spatial resolution of 1000 km or more it is likely that…

Solar and Stellar Astrophysics · Physics 2012-06-07 David H. Brooks , Harry P. Warren , Ignacio Ugarte-Urra

Solar flares signify the sudden release of magnetic energy and are sources of so called space weather. The fine structures (below 500 km) of flares are rarely observed and are accessible to only a few instruments world-wide. Here we present…

Solar and Stellar Astrophysics · Physics 2016-04-29 Ju Jing , Yan Xu , Wenda Cao , Chang Liu , Dale Gary , Haimin Wang

Coronal loops generally trace magnetic lines of force in the upper solar atmosphere. Understanding the loop morphology and its temporal evolution has implications for coronal heating models that rely on plasma heating due to reconnection at…

Solar and Stellar Astrophysics · Physics 2025-01-29 B. Ram , L. P. Chitta , S. Mandal , H. Peter , F. Plaschke

A recent analysis has suggested that the heating of plasma loops in the solar corona depends not just on the Poynting flux but also on processes yet to be identified. This discovery reflects and refines earlier questions such as, why and…

Solar and Stellar Astrophysics · Physics 2024-08-16 P. G. Judge , N. P. M. Kuin

We have numerically demonstrated that simulated cool star coronae naturally form condensations. If the star rotates slowly, with a co-rotation radius greater than the Alfv\'{e}n radius (i.e. $R_{\mathrm{K}} > R_{\mathrm{A}}$), these…

Solar and Stellar Astrophysics · Physics 2024-09-12 Simon Daley-Yates , Moira Jardine

Transverse MHD waves permeate the solar atmosphere and are a candidate for coronal heating. However, the origin of these waves is still unclear. In this work, we analyse coordinated observations from \textit{Hinode}/SOT and \textit{IRIS} of…

Solar and Stellar Astrophysics · Physics 2018-07-25 Patrick Antolin , Paolo Pagano , Ineke De Moortel , Valery M. Nakariakov

We report on the properties of coronal loop foot-point heating with observations at the highest resolution, from the CRisp Imaging Spectro-Polarimeter (CRISP) located at the Swedish 1-m Solar Telescope (SST) and co-aligned NASA Solar…

Solar and Stellar Astrophysics · Physics 2021-11-24 V. N. Nived , E. Scullion , J. G. Doyle , R. Susino , P. Antolin , D. Spadaro , C. Sasso , S. Sahin , M. Mathioudakis

Coronal seismology is extensively used to estimate properties of the corona, e.g. the coronal magnetic field strength are derived from oscillations observed in coronal loops. We present a three-dimensional coronal simulation including a…

Solar and Stellar Astrophysics · Physics 2015-09-23 Feng Chen , Hardi Peter

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

The effect of temperature inhomogeneity on the periods, their ratios (fundamental vs. first overtone), and the damping times of the standing slow modes in gravitationally stratified solar coronal loops are studied. The effects of optically…

Solar and Stellar Astrophysics · Physics 2015-06-05 A. Abedini , H. Safari , S. Nasiri

The Sun's corona is millions of degrees hotter than its 5,000 K photosphere. This heating enigma is typically addressed by invoking the deposition at coronal heights of non-thermal energy generated by the interplay between convection and…

Solar and Stellar Astrophysics · Physics 2009-08-11 Bart De Pontieu , Scott W. McIntosh , Viggo H. Hansteen , Carolus J. Schrijver

We investigate the thermal properties of a solar flare by the observations of soft X-ray Telescope (XRT) on board Hinode and the Atmospheric Image Assembly on board the Solar Dynamics Observatory (SDO/AIA). Our analysis reveals a tenuous…

Solar and Stellar Astrophysics · Physics 2025-10-22 Xiaoyan Xie , Anna Chen , Crisel Suarez , Katharine K. Reeves , Soumya Roy , Christopher S. Moore , Nishu Karna , Joy Velasquez

The heating of solar coronal loops is at the center of the problem of coronal heating. Given that the origin of the fast solar wind has been tracked down to atmospheric layers with transition region or even chromospheric temperatures, it is…

Solar and Stellar Astrophysics · Physics 2014-06-05 Bo Li , Haixia Xie , Xing Li , Li-Dong Xia

A differential emission measure (DEM) method is used to evaluate the relationship of the electron density and temperature before and after a coronal rain event during an active sun over the period from 20:10 UT on October 6 to 02:10 on…

Solar and Stellar Astrophysics · Physics 2021-10-05 Z. M. Vashalomidze , T. V. Zaqarashvili , V. D. Kukhianidze

Coronal loops are the basic building block of the upper solar atmosphere. Comprehending how these are energized, structured, and evolve is key to understanding stellar coronae. Here we investigate how the energy to heat the loop is…

Solar and Stellar Astrophysics · Physics 2022-02-09 C. Breu , H. Peter , R. Cameron , S. K. Solanki , D. Przybylski , M. Rempel , L. P. Chitta

Any successful model of coronal loops must explain a number of observed properties. For warm (~ 1 MK) loops, these include: 1. excess density, 2. flat temperature profile, 3. super-hydrostatic scale height, 4. unstructured intensity…

Solar and Stellar Astrophysics · Physics 2014-11-20 J. A. Klimchuk , J. T. Karpen , S. K. Antiochos

We examine the radiative cooling of coronal loops and demonstrate that the recently identified catastrophic cooling (Reale and Landi, 2012) is due to the inability of a loop to sustain radiative / enthalpy cooling below a critical…

Solar and Stellar Astrophysics · Physics 2015-06-16 Peter J. Cargill , Stephen J. Bradshaw

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

Solar coronal loops show significant plasma motions during their formation and eruption stages. Dynamic cool coronal structures, on the other hand, are often observed to propagate along coronal loops. In this paper, we report on the…

Space Physics · Physics 2015-05-14 J. Zhang , L. P. Li