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Related papers: Spatiotemporal Low FIP Abundance: A Catalyst for C…

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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

The brightness of the emission from coronal loops in the solar atmosphere is strongly dependent on the temperature and density of the confined plasma. After a release of energy, these loops undergo a heating and upflow phase, followed by a…

Solar and Stellar Astrophysics · Physics 2019-03-20 C. D. Johnston , S. J. Bradshaw

We use a combination of analytical theory, numerical simulation, and data analysis to study the propagation of acoustic waves along coronal loops. We show that the intensity perturbation of a wave depends on a number of factors, including…

Astrophysics · Physics 2009-11-10 J. A. Klimchuk , S. E. M. Tanner , I. De Moortel

We outline and discuss a model for the enhanced abundances of trans-Fe elements in impulsive Solar Energetic Particle (SEP) events, where large mass dependent abundance enhancements are frequently seen. It comes about as a variation of the…

Solar and Stellar Astrophysics · Physics 2023-07-12 J. Martin Laming , Natsuha Kuroda

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

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

Coronal plasma in the cores of solar active regions is impulsively heated to more than 5 MK. The nature and location of the magnetic energy source responsible for such impulsive heating is poorly understood. Using observations of seven…

Solar and Stellar Astrophysics · Physics 2020-12-21 L. P. Chitta , H. Peter , E. R. Priest , S. K. Solanki

Emerging dimming occurs in isolated solar active regions (ARs) during the early stages of magnetic flux emergence. Observed by the Atmospheric Imaging Assembly, it features a rapid decrease in extreme-ultraviolet (EUV) emission in the 171…

Solar and Stellar Astrophysics · Physics 2021-05-05 Anna V. Payne , Xudong Sun

The Inverse First Ionization Potential (FIP) Effect, the depletion in coronal abundance of elements like Fe, Mg, and Si that are ionized in the solar chromosphere relative to those that are neutral, has been identified in several solar…

Solar and Stellar Astrophysics · Physics 2021-03-17 J. Martin Laming

We have used Chandra to resolve the nearby 70 Oph (K0 V+K5 V) and 36 Oph (K1 V+K1 V) binary systems for the first time in X-rays. The LETG/HRC-S spectra of all four of these stars are presented and compared with an archival LETG spectrum of…

Astrophysics · Physics 2009-11-11 Brian E. Wood , Jeffrey L. Linsky

It has been established that cold plasma condensations can form in a magnetic loop subject to localized heating of the footpoints. In this paper, we use grid-adaptive numerical simulations of the radiative hydrodynamic equations to…

Solar and Stellar Astrophysics · Physics 2015-05-28 C. Xia , P. F. Chen , R. Keppens , A. J. van Marle

Ponderomotive acceleration has been asserted to be a cause of the First Ionization Potential (FIP) effect, the by now well known enhancement in abundance by a factor of 3-4 over photospheric values of elements in the solar corona with FIP…

Solar and Stellar Astrophysics · Physics 2016-11-15 R. B. Dahlburg , J. M. Laming , B. D. Taylor , K. Obenschain

The outer atmosphere of the Sun is composed of plasma heated to temperatures well in excess of the visible surface. We investigate short cool and warm (<1 MK) loops seen in the core of an active region to address the role of field-line…

Within the coronae of stars, abundances of those elements with low first ionization potential (FIP) often differ from their photospheric values. The coronae of the Sun and solar-type stars mostly show enhancements of low-FIP elements (the…

Context. Observations of slow magnetoacoustic waves in solar coronal loops suggest that, in hot coronal plasma, heat conduction may be suppressed in comparison with the classical thermal transport model. Aims. We link this suppression with…

Solar and Stellar Astrophysics · Physics 2025-01-15 S. A. Belov , T. Goffrey , T. D. Arber , D. Y. Kolotkov

Recent observations have demonstrated that waves which are capable of carrying large amounts of energy are ubiquitous throughout the solar corona. However, the question of how this wave energy is dissipated (on which time and length scales)…

Solar and Stellar Astrophysics · Physics 2014-11-20 Jiajia Liu , Scott W. McIntosh , Ineke De Moortel , James Threlfall , Christian Bethge

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 the effect of a variable, i.e. time-dependent, background on the standing acoustic (i.e. longitudinal) modes generated in a hot coronal loop. A theoretical model of 1D geometry describing the coronal loop is applied. The…

Solar and Stellar Astrophysics · Physics 2012-04-02 K. S. Al-Ghafri , R. Erdélyi

The processes of the coronal plasma heating and cooling were previously shown to significantly affect the dynamics of slow magnetoacoustic (MA) waves, causing amplification or attenuation, and also dispersion. However, the entropy mode is…

Solar and Stellar Astrophysics · Physics 2021-06-23 D. I. Zavershinskii , D. Y. Kolotkov , D. S. Riashchikov , N. E. Molevich

The chemical composition of the solar corona is different from that of the solar photosphere, with the strongest variation being observed in active regions (ARs). Using data from the Extreme Ultraviolet (EUV) Imaging Spectrometer (EIS) on…