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The RS CVn type binary star GT Mus was observed during its quiescence using the Resolve X-ray microcalorimeter spectrometer onboard XRISM. The main and satellite lines of the Fe XXIV--XXVI K-shell transitions were resolved for the first…

Coronal holes (CH) are regions of open magnetic field lines in the solar corona and the source of fast solar wind. Understanding the evolution of coronal holes is critical for solar magnetism as well as for accurate space weather forecasts.…

Space Physics · Physics 2018-05-02 Amr Hamada , Timo Asikainen , Ilpo Virtanen , Kalevi Mursula

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

Solar flares result in an increase of the solar irradiance at all wavelengths. While the distribution of the flare fluence observed in coronal emission has been widely studied and found to scale as f(E) ~ E^{-\alpha}, with \alpha slightly…

Solar and Stellar Astrophysics · Physics 2015-10-08 M. Kretzschmar

Atmospheric temperatures are to be estimated from thermal emission spectra of Earth-like exoplanets orbiting M-stars as observed by current and future planned missions. To this end, a line-by-line radiative transfer code is used to generate…

Earth and Planetary Astrophysics · Physics 2023-06-02 Franz Schreier , J. Lee Grenfell , Fabian Wunderlich , Thomas Trautmann

All but the most massive main-sequence stars are expected to have a rarefied and hot (million-Kelvin) corona like the Sun. How such a hot corona is formed and supported has not been completely understood yet, even in the case of the Sun.…

Solar and Stellar Astrophysics · Physics 2025-02-12 Luca Barbieri , Lapo Casetti , Andrea Verdini , Simone Landi

In previous studies a very hot plasma component has been diagnosed in solar active regions through the images in three different narrow-band channels of SDO/AIA. This diagnostic from EUV imaging data has also been supported by the matching…

Solar and Stellar Astrophysics · Physics 2015-06-18 A. Petralia , F. Reale , P. Testa , G. Del Zanna

ALMA observations of the Sun at mm-$\lambda$ offer a unique opportunity to investigate the temperature structure of the solar chromosphere. In this article we expand our previous work on modeling the chromospheric temperature of the quiet…

Solar and Stellar Astrophysics · Physics 2020-08-19 C. E. Alissandrakis , A. Nindos , T. S. Bastian , S. Patsourakos

Context: A large number of the small and the short-lived EUV brightenings have been detected in the quiet Sun (QS) over the past three years, by the High Resolution Imager of the Extreme Ultraviolet Imager (HRIEUV) on board Solar Orbiter.…

Solar and Stellar Astrophysics · Physics 2024-08-09 A. Dolliou , S. Parenti , K. Bocchialini

Differential Emission Measure (DEM) inversion methods use the brightness of a set of emission lines to infer the line-of-sight (LOS) distribution of the electron temperature ($T_e$) in the corona. DEM inversions have been traditionally…

Solar and Stellar Astrophysics · Physics 2023-07-12 Benjamin Boe , Cooper Downs , Shadia Habbal

We present spatially resolved X-ray spectra taken with the EPIC cameras of XMM-Newton of a sample of 17 cooling clusters and three non-cooling clusters for comparison. The deprojected spectra are analyzed with a multi-temperature model,…

We report observations of type III radio bursts at decimeter wavelengths (type IIIdm bursts) -- signatures of suprathermal electron beams propagating in the low corona -- using the new technique of radio dynamic imaging spectroscopy…

Solar and Stellar Astrophysics · Physics 2015-06-12 Bin Chen , Timothy S. Bastian , Stephen M. White , Dale E. Gary , Richard A. Perley , Michael P. Rupen , Brent R. Carlson

Coronal holes (CHs) are regions of open magnetic flux which are the source of high speed solar wind (HSSW) streams. To date, it is not clear which aspects of CHs are of most influence on the properties of the solar wind as it expands…

Solar and Stellar Astrophysics · Physics 2018-12-12 Tadhg M. Garton , Sophie A. Murray , Peter T. Gallagher

Measuring the temperature structure of the solar atmosphere is critical to understanding how it is heated to high temperatures. Unfortunately, the temperature of the upper atmosphere cannot be observed directly, but must be inferred from…

Solar and Stellar Astrophysics · Physics 2017-03-08 Harry P. Warren , Jeff M. Byers , Nicholas A. Crump

Poynting flux generated by random shuffling of photospheric magnetic footpoints is transferred through the upper atmosphere of the Sun where the plasma is heated to over 1 MK in the corona. High spatiotemporal resolution observations of the…

Solar and Stellar Astrophysics · Physics 2024-11-20 L. P. Chitta , M. van Noort , H. N. Smitha , E. R. Priest , L. H. M. Rouppe van der Voort

Metrewave solar type-III radio bursts offer a unique means to study the properties of turbulence across the coronal heights.Theoretical models have shown that the apparent intensity and size of the burst sources evolve at sub-second scales…

Solar and Stellar Astrophysics · Physics 2021-11-24 Atul Mohan

Three dimensional electron density distributions in the solar corona are reconstructed for 100 Carrington Rotations (CR 2054$-$2153) during 2007/03$-$2014/08 using the spherically symmetric method from polarized white-light observations…

Solar and Stellar Astrophysics · Physics 2017-07-25 Tongjiang Wang , Nelson L. Reginald , Joseph M. Davila , O. Chris St. Cyr , William T. Thompson

In the solar corona, several mechanisms of the drift wave instability can make the mode growing up to amplitudes at which particle acceleration and stochastic heating by the drift wave take place. The stochastic heating, well known from…

Solar and Stellar Astrophysics · Physics 2015-05-19 J. Vranjes , S. Poedts

The thermodynamic evolution of Coronal Mass Ejections (CMEs) in the inner corona (< 1.5 R$_{sun}$) is not yet completely understood. In this work, we study the evolution of thermodynamic properties of a CME core observed in the inner corona…

Solar and Stellar Astrophysics · Physics 2023-01-31 Jyoti Sheoran , Vaibhav Pant , Ritesh Patel , Dipankar Banerjee

Images taken in the band centered at 30.4 nm are routinely used to map the radiance of the He II Ly alpha line on the solar disk. That line is one of the strongest, if not the strongest, line in the EUV observed in the solar spectrum, and…

Solar and Stellar Astrophysics · Physics 2014-01-30 V. Andretta , D. Telloni , G. Del Zanna