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We proposed that the use of an approximate "jump condition" at the solar transition region permits fast and accurate numerical solutions of the one dimensional hydrodynamic equations when the corona undergoes impulsive heating. In…

Solar and Stellar Astrophysics · Physics 2017-08-30 C. D. Johnston , A. W. Hood , P. J. Cargill , I. De Moortel

Magnetic energy released in the corona by solar flares reaches the chromosphere where it drives characteristic upflows and downflows known as evaporation and condensation. These flows are studied here for the case where energy is…

Solar and Stellar Astrophysics · Physics 2015-06-22 D. W. Longcope

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

The effect of the numerical spatial resolution in models of the solar corona and corona / chromosphere interface is examined for impulsive heating over a range of magnitudes using one dimensional hydrodynamic simulations. It is demonstrated…

Solar and Stellar Astrophysics · Physics 2015-06-15 Stephen J. Bradshaw , Peter J. Cargill

We develop a three-dimensional kinetic model of the solar transition region and corona in which the plasma above the chromosphere is collisionless and embedded in a uniform magnetic field. Heating occurs intermittently at discrete locations…

Solar and Stellar Astrophysics · Physics 2026-01-14 Luca Barbieri , Pascal Démoulin

Magnetic reconnection in the corona results in contracting flare loops, releasing energy into plasma heating and shocks. The hydrodynamic shocks so produced drive thermal conduction fronts (TCFs) which transport energy into the chromosphere…

Solar and Stellar Astrophysics · Physics 2015-06-22 Sean Brannon , Dana Longcope

Coupling between the photosphere, chromosphere and corona in the quiet Sun (QS) is governed by a complex interplay between magnetic structuring, heating, mass loading, and radiative cooling. Constraining how this balance responds to…

Solar and Stellar Astrophysics · Physics 2026-05-19 Quentin Noraz , Mats Carlsson , Guillaume Aulanier

It remains unclear which physical processes are responsible for the dramatic increase with height of the temperature in stellar atmospheres, known as the chromospheric ($\sim$10,000 K) and coronal (several million K) heating problems.…

Solar and Stellar Astrophysics · Physics 2022-11-17 Souvik Bose , Bart De Pontieu , Viggo Hansteen , Alberto Sainz Dalda , Sabrina Savage , Amy Winebarger

Modelling the solar Transition Region with the use of an Adaptive Conduction (TRAC) method permits fast and accurate numerical solutions of the field-aligned hydrodynamic equations, capturing the enthalpy exchange between the corona and…

Solar and Stellar Astrophysics · Physics 2020-04-01 C. D. Johnston , P. J. Cargill , A. W. Hood , I. De Moortel , S. J. Bradshaw , A. C. Vaseekar

The origin of the slow solar wind is still an open issue. It has been suggested that upflows at the edge of active regions (AR) can contribute to the slow solar wind. Here, we compared the upflow region and the AR core and studied how the…

Solar and Stellar Astrophysics · Physics 2021-08-04 Krzysztof Barczynski , Louise Harra , Lucia Kleint , Brandon Panos , David H. Brooks

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

An expansion of cross-sectional area directly impacts the mass flow along a coronal loop, and significantly alters the radiative and hydrodynamic evolution of that loop as a result. Previous studies have found that an area expansion from…

Solar and Stellar Astrophysics · Physics 2024-03-20 Jeffrey W. Reep , Roger B. Scott , Sherry Chhabra , John Unverferth , Kalman J. Knizhnik

High resolution spectral observations of the lower solar atmosphere (chromosphere and transition region) during coronal heating events, in combination with predictions from models of impulsively heated loops, provide powerful diagnostics of…

Solar and Stellar Astrophysics · Physics 2023-11-01 Paola Testa , Helle Bakke , Luc Rouppe van der Voort , Bart De Pontieu

We point out the priority of our paper (Mahajan et al. 2001, Phys. Plasmas, 8, 1340) over (Aschwanden et al. 2007, Astrophys J., 659, 1673) in introducing the term "Formation and primary heating of the solar corona" working out explicit…

Astrophysics · Physics 2007-09-12 Swadesh M. Mahajan , Nana L. Shatashvili

This work addresses the problem of plasma condensation and ``catastrophic cooling'' in solar coronal loops. We have carried out numerical calculations of coronal loops and find several classes of time-dependent solutions (static, periodic,…

Astrophysics · Physics 2009-11-10 D. A. N. Mueller , H. Peter , V. H. Hansteen

The large temperature gradients in the solar transition region present a significant challenge to large scale numerical modelling of the Sun's atmosphere. In response, a variety of techniques have been developed which modify the…

Solar and Stellar Astrophysics · Physics 2023-09-13 Thomas Howson , Cosima Breu

Minimal observational evidence exists for fast transition region (TR) upflows in the presence of cool loops. Observations of such occurrences challenge notions of standard solar atmospheric heating models, as well as their description of…

Solar and Stellar Astrophysics · Physics 2016-01-13 N. B. Orange , D. L. Chesny , H. M. Oluseyi , K. Hesterly , M. Patel , P. R. Champey

Observational evidence for gentle chromospheric evaporation during the impulsive phase of a C9.1 solar flare is presented using data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager and the Coronal Diagnostic Spectrometer on…

The physical processes causing energy exchange between the Sun's hot corona and its cool lower atmosphere remain poorly understood. The chromosphere and transition region (TR) form an interface region between the surface and the corona that…

In this work we describe our implementation of a thermodynamic energy equation into the global corona model of the Space Weather Modeling Framework (SWMF), and its development into the new Lower Corona (LC) model. This work includes the…

Solar and Stellar Astrophysics · Physics 2014-11-20 Cooper Downs , Ilia I. Roussev , Bart van der Holst , Noé Lugaz , Igor V. Sokolov , Tamas I. Gombosi
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