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Coronal loops are the building blocks of the X-ray bright solar corona. They owe their brightness to the dense confined plasma, and this review focuses on loops mostly as structures confining plasma. After a brief historical overview, the…

Solar and Stellar Astrophysics · Physics 2015-05-20 Fabio Reale

Recent observations of reflected propagating and standing slow-mode waves in hot flaring coronal loops have spurred our investigation into their underlying excitation and damping mechanisms. To understand these processes, we conduct 2.5D…

Solar and Stellar Astrophysics · Physics 2024-04-01 Tongjiang Wang , Leon Ofman , Stephen J. Bradshaw

We present a study of the temporal evolution of coronal loops in active regions and its implications for the dynamics in coronal loops. We analyzed images of the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) at…

Solar and Stellar Astrophysics · Physics 2011-08-09 S. Kamio , H. Peter , W. Curdt , S. K. Solanki

It is generally agreed that small impulsive energy bursts called nanoflares are responsible for at least some of the Sun's hot corona, but whether they are the explanation for most of the multi-million degree plasma has been a matter of…

Solar and Stellar Astrophysics · Physics 2015-05-28 Sergio Terzo , Fabio Reale , Marco Miceli , James A. Klimchuk , Ryouhei Kano , Saku Tsuneta

Flares are dynamic events which involve rapid changes in coronal magnetic topology end energy release. Even if they may be localized phenomena, the magnetic disturbance at their origin may propagate and be effective in a larger part of the…

Solar and Stellar Astrophysics · Physics 2010-10-18 S. Parenti , F. Reale , K. K. Reeves

We present results of a multi-wavelength study of episodic plasma injection into the corona of AR 10942. We exploit long-exposure images of the Hinode and Transition Region and Coronal Explorer (TRACE) spacecraft to study the properties of…

Solar and Stellar Astrophysics · Physics 2014-11-20 Scott W. McIntosh , Bart De Pontieu

An analytical MHD model of coronal loops with compressible flows and including heating is compared to observational data. The model is constructed via a systematic nonlinear separation of the variables method used to calculate several…

Astrophysics · Physics 2009-11-07 G. J. D. Petrie , C. Gontikakis , H. Dara , K. Tsinganos , M. J. Aschwanden

We present observations of high temperature emission in the core of a solar active region using instruments on Hinode and SDO. These multi-instrument observations allow us to determine the distribution of plasma temperatures and follow the…

Solar and Stellar Astrophysics · Physics 2015-05-20 Harry P. Warren , David H. Brooks , Amy R. Winebarger

A set-up is introduced which can be superimposed onto the existing solar flare cellular automata (CA) models, and which specifies the interpretation of the model's variables. It extends the CA models, yielding the magnetic field, the…

Astrophysics · Physics 2007-05-23 H. Isliker , A. Anastasiadis , L. Vlahos

We numerically explore electron acceleration and coronal heating by dissipative electric fields. Electrons are traced in linear force-free magnetic fields extrapolated from SOHO/MDI magnetograms, endowed with anomalous resistivity ($\eta$)…

Astrophysics · Physics 2009-11-11 Kaspar Arzner , Loukas Vlahos

I propose a new paradigm for solar coronal heating viewed as a self-regulating process keeping the plasma marginally collisionless. The mechanism is based on the coupling between two effects. First, coronal density controls the plasma…

Astrophysics · Physics 2008-11-26 Dmitri A. Uzdensky

Despite extensive observational and theoretical efforts, the physical processes responsible for shaping the diversity of accelerated electron spectra observed in solar flares remain poorly understood. We use 2D particle-in-cell (PIC)…

Solar and Stellar Astrophysics · Physics 2025-10-01 Martín Astete , Mario Riquelme , Daniel Verscharen

Outflows of plasma at the edges of active regions surrounded by quiet Sun are now a common observation with the Hinode satellite. While there is observational evidence to suggest that the outflows are originating in the magnetic field…

Solar and Stellar Astrophysics · Physics 2015-05-14 M. J. Murray , D. Baker , L. van Driel-Gesztelyi , J. Sun

As one of the most spectacular energy release events in the solar system, solar flares are generally powered by magnetic reconnection in the solar corona. As a result of the re-arrangement of magnetic field topology after the reconnection…

Solar and Stellar Astrophysics · Physics 2021-03-29 Tanmoy Samanta , Hui Tian , Bin Chen , Katharine K. Reeves , Mark C. M. Cheung , Angelos Vourlidas , Dipankar Banerjee

Nanoflare heating through small-scale magnetic reconnection events is one of the prime candidates to explain heating of the solar corona. However, direct signatures of nanoflares are difficult to determine, and unambiguous observational…

Solar and Stellar Astrophysics · Physics 2023-07-12 H. Bakke , L. Frogner , L. Rouppe van der Voort , B. V. Gudiksen , M. Carlsson

A Cellular Automata (CA) rule is presented that can generate "loop patterns" in a 2D grid under fixed boundary conditions. A loop is a cyclically closed path represented by one-cells enclosed by zero-cells. A loop pattern can contain…

Cellular Automata and Lattice Gases · Physics 2025-05-30 Rolf Hoffmann , Mariusz Białecki

To adequately constrain the frequency of energy deposition in active region cores in the solar corona, systematic comparisons between detailed models and observational data are needed. In this paper, we describe a pipeline for forward…

Solar and Stellar Astrophysics · Physics 2019-07-31 W. T. Barnes , S. J. Bradshaw , N. M. Viall

Due to their characteristic temperature and density, loop structures in active regions (ARs) can be seen bright in extreme ultraviolet (EUV) and soft X-ray images. The semiempirical determination of the three-dimensional (3D) distribution…

Solar and Stellar Astrophysics · Physics 2020-12-16 F. A. Nuevo , C. Mac Cormack , M. López Fuentes , A. M. Vásquez , C. H. Mandrini

Coronal plasma in the cores of solar active regions is impulsively heated to more than 5 MK. The nature and location of the magnetic energy source responsible for such impulsive heating is poorly understood. Using observations of seven…

Solar and Stellar Astrophysics · Physics 2020-12-21 L. P. Chitta , H. Peter , E. R. Priest , S. K. Solanki

Impulsive nanoflares are expected to transiently heat the plasma confined in coronal loops to temperatures of the order of 10 MK. Such hot plasma is hardly detected in quiet and active regions, outside flares. During rapid and short heat…

Astrophysics · Physics 2009-11-13 Fabio Reale , Salvatore Orlando