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We investigate the thermal, kinematic and magnetic structure of small-scale heating events in an emerging flux region (EFR). We use high-resolution multi-line observations (including Ca II 8542~\AA, Ca II K, and Fe I 6301~\AA line pair) of…

Solar and Stellar Astrophysics · Physics 2023-09-14 Rahul Yadav , Maria D. Kazachenko , Andrey N. Afanasyev , Jaime de la Cruz Rodríguez , Jorrit Leenaarts

The heating of the solar corona and the puzzle of the slender high reaching magnetic loops seen in observations from the Transition Region And Coronal Explorer(TRACE) has been investigated through 3D numerical simulations, and found to be…

Astrophysics · Physics 2007-05-23 Boris V. Gudiksen , Aake Nordlund

What physical mechanisms heat the outer solar or stellar atmosphere to million-Kelvin temperatures is a fundamental but long-standing open question. In particular, the solar corona in active region cores contains an even hotter component…

Solar and Stellar Astrophysics · Physics 2024-04-09 Zekun Lu , Feng Chen , M. D. Ding , Can Wang , Yu Dai , Xin Cheng

We use the cellular automaton model described in L\'opez Fuentes \& Klimchuk (2015, ApJ, 799, 128) to study the evolution of coronal loop plasmas. The model, based on the idea of a critical misalignment angle in tangled magnetic fields,…

Solar and Stellar Astrophysics · Physics 2016-09-21 Marcelo López Fuentes , James A. Klimchuk

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

Dense plasma fragments were observed to fall back on the solar surface by the Solar Dynamics Observatory after an eruption on 7 June 2011, producing strong EUV brightenings. Previous studies investigated impacts in regions of weak magnetic…

Solar and Stellar Astrophysics · Physics 2016-11-15 A. Petralia , F. Reale , S. Orlando , P. Testa

A recent study demonstrated that freedom of convection and strength of magnetic field in the photospheric feet of active-region (AR) coronal loops, together, can engender or quench heating in them. Other studies stress that magnetic flux…

Solar and Stellar Astrophysics · Physics 2021-02-23 Sanjiv K. Tiwari , Caroline L. Evans , Navdeep K. Panesar , Avijeet Prasad , Ronald L. Moore

The variation of the vector magnetic field along structures in the solar corona remains unmeasured. Using a unique combination of spectropolarimetry and stereoscopy, we infer and compare the vector magnetic field structure and…

Solar and Stellar Astrophysics · Physics 2016-12-14 Thomas A. Schad , Matthew J. Penn , Haosheng Lin , Philip G. Judge

Standing slow mode waves in hot flaring loops are exclusively observed in spectrometers and are used to diagnose the magnetic field strength and temperature of the loop structure. Due to the lack of spatial information, the longitudinal…

Solar and Stellar Astrophysics · Physics 2015-07-15 D. Yuan , T. Van Doorsselaere , D. Banerjee , P. Antolin

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

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

Short heat pulses can trigger plasma pressure fronts inside closed magnetic tubes in the corona. The alternation of condensations and rarefactions from the pressure modes drive large-amplitude pulsations in the plasma emission. Here we show…

Solar and Stellar Astrophysics · Physics 2019-11-06 Fabio Reale , Paola Testa , Antonino Petralia , Dmitrii Y. Kolotkov

MHD waves permeate the solar atmosphere and constitute potential coronal heating agents. Yet, the waves detected so far may be but a small subset of the true existing wave power. Detection is limited by instrumental constraints, but also by…

Solar and Stellar Astrophysics · Physics 2017-02-03 Patrick Antolin , Ineke De Moortel , Tom Van Doorsselaere , Takaaki Yokoyama

Recurrent and propagating intensity perturbations are frequently observed in extreme ultraviolet (EUV) channels along coronal fan loops above sunspots, and these perturbations are suggested to be slow magnetoacoustic waves. Numerous studies…

Solar and Stellar Astrophysics · Physics 2025-02-26 Junwei Zhao , Tongjiang Wang , Ruizhu Chen

The \textit{Sun Watcher using Active Pixel system detector and Image Processing}(SWAP) on board the \textit{PRoject for OnBoard Autonomy\todash 2} (PROBA\todash 2) spacecraft provides images of the solar corona in EUV channel centered at…

Solar and Stellar Astrophysics · Physics 2012-06-11 K. Chandrashekhar , S. Krishna Prasad , D. Banerjee , B. Ravindra , Daniel B. Seaton

To explain the high temperature of the corona, much attention has been paid to the distribution of energy in dissipation events. Indeed, if the event energy distribution is steep enough, the smallest, unobservable events could be the…

Solar and Stellar Astrophysics · Physics 2016-07-06 Vincent Joulin , Éric Buchlin , Jacques Solomon , Chloé Guennou

Solar flares form and release energy across a large number of magnetic loops. The global parameters of flares, such as the total energy released, duration, physical size, etc., are routinely measured, and the hydrodynamics of a coronal loop…

Solar and Stellar Astrophysics · Physics 2018-04-18 Jeffrey W. Reep , Vanessa Polito , Harry P. Warren , Nicholas A. Crump

The coronal magnetic field evolution of 20 bipolar active regions (ARs) is simulated from their emergence to decay using the time-dependent nonlinear force-free field method of Mackay et al. A time sequence of cleaned photospheric…

Solar and Stellar Astrophysics · Physics 2021-01-13 Stephanie L. Yardley , Duncan H. Mackay , Lucie M. Green

Quasi-periodic propagating disturbances in coronal structures have been interpreted as slow magneto-acoustic waves and/or periodic upflows. Here we aim to understand their nature from the observed properties using a three-hour imaging…

Solar and Stellar Astrophysics · Physics 2015-06-11 S. Krishna Prasad , D. Banerjee , T. Van Doorsselaere , J. Singh

Coronal loops are fundamental building blocks of the solar active regions and the corona. Therefore, a clear understanding of the physics of coronal loops will help us understand the physics of active region heating in particular and…

Solar and Stellar Astrophysics · Physics 2011-02-11 D. Tripathi , H. E. Mason , B. N. Dwivedi , G. Del Zanna , P. R. Young