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Quasi-constant heating at the footpoints of loops leads to evaporation and condensation cycles of the plasma: thermal non-equilibrium (TNE). This phenomenon is believed to play a role in the formation of prominences and coronal rain.…

Solar and Stellar Astrophysics · Physics 2015-08-27 Clara Froment , Frédéric Auchère , Karine Bocchialini , Eric Buchlin , Chloé Guennou , Jacques Solomon

Using the "enthalpy-based thermal evolution of loops" (EBTEL) model, we investigate the hydrodynamics of the plasma in a flaring coronal loop in which heat conduction is limited by turbulent scattering of the electrons that transport the…

Solar and Stellar Astrophysics · Physics 2018-01-31 Nicolas Bian , A. Gordon Emslie , Duncan Horne , Eduard P. Kontar

Solar flare X-ray spectra are typically dominated by thermal bremsstrahlung emission in the soft X-ray ($\lesssim$10 keV) energy range; for hard X-ray energies ($\gtrsim$30 keV), emission is typically non-thermal from beams of electrons.…

Solar and Stellar Astrophysics · Physics 2020-04-08 James M. McTiernan , Amir Caspi , Harry P. Warren

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,…

Daily differential emission measure (DEM) distributions of the solar corona are derived from spectra obtained by the Extreme-ultraviolet Variability Experiment (EVE) over a 4-year period starting in 2010 near solar minimum and continuing…

Solar and Stellar Astrophysics · Physics 2020-09-16 Samuel J. Schonfeld , Stephen M. White , Rachel A. Hock-Mysliwiec , R. T. James McAteer

We analyze and model an M8.0 flare on 2005 May 13 observed by TRACE and RHESSI to determine the energy release rate from magnetic reconnection that forms and heats numerous flare loops. The flare exhibits two ribbons in UV 1600 {\AA}…

Solar and Stellar Astrophysics · Physics 2014-06-25 Wen-Juan Liu , Jiong Qiu , Dana W. Longcope , Amir Caspi

Rapidly decaying slow magnetoacoustic waves are regularly observed in the solar coronal structures, offering a promising tool for a seismological diagnostics of the coronal plasma, including its thermodynamical properties. The effect of…

Solar and Stellar Astrophysics · Physics 2019-08-21 D. Y. Kolotkov , V. M. Nakariakov , D. I. Zavershinskii

We study the thermal evolution of primordial star-forming gas clouds using three-dimensional cosmological simulations. We critically examine how assumptions and approximations made in calculating radiative cooling rates affect the dynamics…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-20 Shingo Hirano , Naoki Yoshida

X-Ray and Ultraviolet (UV) observations of the outer solar atmosphere have been used for many decades to measure the fundamental parameters of the solar plasma. This review focuses on the optically thin emission from the solar atmosphere,…

Solar and Stellar Astrophysics · Physics 2018-09-06 Giulio Del Zanna , Helen E. Mason

It is generally accepted that densities of quiet sun and active region plasma are sufficiently low to justify the optically thin approximation, and it is commonly used in the analysis of line emissions from plasma in the solar corona.…

Solar and Stellar Astrophysics · Physics 2018-02-14 Edward Thiemann , Phillip Chamberlin , Francis Eparvier , Luke Epp

We examine the hypothesis that ``cool loops'' dominate emission from solar transition region plasma below temperatures of $2\times10^5$K. We compare published VAULT images of H L$\alpha$, a lower transition region line, with…

Astrophysics · Physics 2009-11-13 Philip G. Judge , Rebecca Centeno

We study the thermophysical properties of dense helium plasmas by using quantum molecular dynamics and orbital-free molecular dynamics simulations, where densities are considered from 400 to 800 g/cm$^{3}$ and temperatures up to 800 eV.…

Materials Science · Physics 2011-06-27 Cong Wang , Xian-Tu He , Ping Zhang

Context. The radiative losses in the solar chromosphere vary from 4~kW~m$^{-2}$ in the quiet Sun, to 20~kW~m$^{-2}$ in active regions. The mechanisms that transport non-thermal energy to and deposit it in the chromosphere are still not…

Solar and Stellar Astrophysics · Physics 2018-04-18 Jorrit Leenaarts , Jaime de la Cruz Rodríguez , Sanja Danilovic , Göran Scharmer , Mats Carlsson

Evidence for small amounts of very hot plasma has been found in active regions and might be the indication of an impulsive heating, released at spatial scales smaller than the cross section of a single loop. We investigate the heating and…

Solar and Stellar Astrophysics · Physics 2016-01-13 E. Tajfirouze , F. Reale , A. Petralia , P. Testa

Laser cooling of solids currently has a temperature floor of 50 - 100 K. We propose a method that could overcome this using defects, such as diamond color centers, with narrow electronic manifolds and bright optical transitions. It exploits…

Mesoscale and Nanoscale Physics · Physics 2024-10-08 Luisa Toledo Tude , Conor N. Murphy , Paul R. Eastham

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

The distribution of temperature and emission measure in the stationary heated solar atmosphere was obtained for the limiting cases of slow and fast heating, when either the gas pressure or the concentration are constant throughout the layer…

Solar and Stellar Astrophysics · Physics 2010-04-16 O. Ptitsyna , B. Somov

Flare loops form an integral part of eruptive events, being detected in the range of temperatures from X-rays down to cool chromospheric-like plasmas. While the hot loops are routinely observed by the Solar Dynamics Observatory's…

Solar and Stellar Astrophysics · Physics 2020-01-08 Július Koza , David Kuridze , Petr Heinzel , Sonja Jejčič , Huw Morgan , Maciej Zapiór

The relationships among coronal loop structures at different temperatures is not settled. Previous studies have suggested that coronal loops in the core of an active region are not seen cooling through lower temperatures and therefore are…

Solar and Stellar Astrophysics · Physics 2011-02-11 Ignacio Ugarte-Urra , Harry P. Warren , David H. Brooks

Previous observations have not been able to exclude the possibility that high temperature active region loops are actually composed of many small scale threads that are in various stages of heating and cooling and only appear to be in…

Solar and Stellar Astrophysics · Physics 2014-11-20 Harry P. Warren , Amy R. Winebarger , David H. Brooks
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