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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

The thermal stability of rotating, stratified, unmagnetized atmospheres is studied by means of linear-perturbation analysis, finding stability, overstability or instability, depending on the properties of the gas distribution, but also on…

Astrophysics of Galaxies · Physics 2015-05-18 Carlo Nipoti

EUV observations of warm coronal loops suggest that they are bundles of unresolved strands that are heated impulsively to high temperatures by nanoflares. The plasma would then have the observed properties (e.g., excess density compared to…

Solar and Stellar Astrophysics · Physics 2011-02-11 S. Patsourakos , J. A. Klimchuk

Characterising the large-scale structure and plasma properties of the inner corona is crucial to understand the source and subsequent expansion of the solar wind and related space weather effects. Here we apply a new coronal rotational…

Solar and Stellar Astrophysics · Physics 2020-04-22 Huw Morgan , Anthony C. Cook

The plasma contributing to emission from the Sun between the cool chromosphere ($\le 10^4$K) and hot corona ($\ge 10^6$K) has been subjected to many different interpretations. Here we look at the magnetic structure of this transition region…

Solar and Stellar Astrophysics · Physics 2021-06-23 Philip G. Judge

Some of local sources of the slow solar wind can be associated with spectroscopically detected plasma outflows at edges of active regions accompanied with specific signatures in the inner corona. The EUV telescopes (e.g. SPIRIT/CORONAS-F,…

Solar and Stellar Astrophysics · Physics 2012-05-03 V. Slemzin , L. Harra , A. Urnov , S. Kuzin , F. Goryaev , D. Berghmans

We investigate the scaling properties of the long-range temporal evolution and intermittency of SDO/AIA intensity observations in four solar environments: an active region core, a weak emission region, and two core loops. We use two…

Solar and Stellar Astrophysics · Physics 2016-11-15 Ana Cristina Cadavid , Yeimy J. Rivera , John K. Lawrence , Damian J. Christian , Peter J. Jennings , A. Franco Rappazzo

The prominent blue shifts of Ne viii associated with the junctions of the magnetic network in the quiet Sun are still not well understood. By comparing the coronal magnetic-field structures as obtained by a potential-field reconstruction…

Solar and Stellar Astrophysics · Physics 2014-11-20 Hui Tian , Eckart Marsch , Werner Curdt , Jiansen He

Coronal mass ejections (CMEs) are often associated with coronal dimmings, i.e. transient dark regions that are most distinctly observed in Extreme Ultra-violet (EUV) wavelengths. Using Atmospheric Imaging Assembly (AIA) data, we apply…

Solar and Stellar Astrophysics · Physics 2018-05-02 Kamalam Vanninathan , Astrid M. Veronig , Karin Dissauer , Manuela Temmer

The atmospheres filling massive galaxies, groups, and clusters display remarkable similarities with rainfalls. Such plasma halos are shaped by AGN heating and subsonic turbulence (~150 km/s), as probed by Hitomi. The new 3D high-resolution…

Astrophysics of Galaxies · Physics 2017-01-18 M. Gaspari , P. Temi , F. Brighenti

We estimate the coronal density of Capella using the O VII and Fe XVII line systems in the soft X-ray regime that have been observed over the course of the Chandra mission. Our analysis combines measures of error due to uncertainty in the…

Solar and Stellar Astrophysics · Physics 2024-06-21 Xixi Yu , Vinay L. Kashyap , Giulio Del Zanna , David A. van Dyk , David C. Stenning , Connor P. Ballance , Harry P. Warren

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

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 young active star AB Dor (K1 IV-V) has been observed 16 times in the last three years with the XMM-Newton and Chandra observatories, totalling 650 ks of high-resolution X-ray spectra. The XMM/RGS observations with the highest and lowest…

Astrophysics · Physics 2009-11-10 J. Sanz-Forcada , A. Maggio , G. Micela

Dynamic fibrils (DFs) are commonly observed chromospheric features in solar active regions. Recent observations from the Extreme Ultraviolet Imager (EUI) aboard the Solar Orbiter have revealed unambiguous signatures of DFs at the coronal…

The solar atmosphere shows anomalous variation in temperature, starting from the 5500 K photosphere to the million-degree Kelvin corona. The corona itself expands into the interstellar medium as the free streaming solar wind, which…

Solar and Stellar Astrophysics · Physics 2023-04-05 Vishal Upendran

Coronal rain (CR) is a crucial part of the mass cycle between the corona and chromosphere. It includes the flare-driven CR and two types of quiescent CR separately along the non-flaring active region closed loops and along the open…

Solar and Stellar Astrophysics · Physics 2024-08-15 Fangfang Qiao , Leping Li , Hui Tian , Zhenyong Hou , Hongqiang Song , Kaifan Ji , Zheng Sun

In solar coronal loops, thermal non-equilibrium (TNE) is a phenomenon that can occur when the heating is both highly-stratified and quasi-constant. Unambiguous observational identification of TNE would thus permit to strongly constrain…

Solar and Stellar Astrophysics · Physics 2017-02-08 Clara Froment , Frédéric Auchère , Guillaume Aulanier , Zoran Mikić , Karine Bocchialini , Eric Buchlin , Jacques Solomon

There is reason to suspect that about half of the baryons are in pressure-supported plasma in the halos of normal galaxies, drawn in by gravity along with about half of the dark matter. To be consistent with the observations this baryonic…

Astrophysics · Physics 2008-11-26 Masataka Fukugita , P. J. E. Peebles

Abridged: We study the properties of clumps formed in three-dimensional weakly magnetized magneto-hydrodynamic simulations of converging flows in the thermally bistable, warm neutral medium (WNM). We find that: (1) Similarly to the…

Astrophysics · Physics 2015-05-13 Robi Banerjee , Enrique Vazquez-Semadeni , Patrick Hennebelle , Ralf Klessen