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Related papers: Nanoflare statistics in an active region 3D MHD co…

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The solar atmosphere is known to contain many different types of wavelike oscillation. Waves and other fluctuations (e.g., turbulent eddies) are believed to be responsible for at least some of the energy transport and dissipation that heats…

Solar and Stellar Astrophysics · Physics 2023-08-09 Steven R. Cranmer , Momchil E. Molnar

This paper presents a new model of North Polar Coronal Hole (NPCH) to study dissipation/propagation of MHD waves. We investigate the effects of the isotropic viscosity and heat conduction on the propagation characteristics of the MHD waves…

Solar and Stellar Astrophysics · Physics 2023-06-28 E. Devlen , D. Zengin Çamurdan , M. Yardımcı , E. R. Pekünlü

This paper reviews the latest observational evidence for the existence of propagating waves in the open magnetic flux tubes of the solar corona. SOHO measurements have put tentative limits on the fluxes of various types of…

Astrophysics · Physics 2007-05-23 Steven R. Cranmer

The time-dependence of heating in solar active regions can be studied by analyzing the slope of the emission measure distribution cool-ward of the peak. In a previous study we showed that low-frequency heating can account for 0% to 77% of…

Solar and Stellar Astrophysics · Physics 2013-03-20 Jeffrey W. Reep , Stephen J. Bradshaw , James A. Klimchuk

Solar flares and plasma eruptions are sudden releases of magnetic energy stored in the plasma atmosphere. To understand the physical mechanisms governing their occurrences, three-dimensional magnetic fields from the photosphere up to the…

Solar and Stellar Astrophysics · Physics 2021-03-24 Takafumi Kaneko , Sung-Hong Park , Kanya Kusano

The measured average velocities in solar and stellar spectral lines formed at transition region temperatures have been difficult to interpret. However, realistic three-dimensional radiation magnetohydrodynamics (3D rMHD) models of the solar…

Solar and Stellar Astrophysics · Physics 2018-07-11 P. Zacharias , V. H. Hansteen , J. Leenaarts , M. Carlsson , B. V. Gudiksen

Magnetic reconnection, a fundamentally important process in many aspects of astrophysics, is believed to be initiated by the tearing instability of an electric current sheet, a region where magnetic field abruptly changes direction and…

Solar and Stellar Astrophysics · Physics 2020-03-11 James Leake , Lars Daldorff , James Klimchuk

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

Solar coronal loops are commonly subject to oscillations. Observations of coronal oscillations are used to infer physical properties of the coronal plasma using coronal seismology. Excitation and evolution of oscillations in coronal loops…

Solar and Stellar Astrophysics · Physics 2021-03-17 P. Kohutova , A. Popovas

We present numerical simulations in 3D settings where coronal rain phenomena take place in a magnetic configuration of a quadrupolar arcade system. Our simulation is a magnetohydrodynamic simulation including anisotropic thermal conduction,…

Solar and Stellar Astrophysics · Physics 2016-01-20 S. P. Moschou , R. Keppens , C. Xia , X. Fang

We present in this Letter the first global comparison between traditional line-tied steady state magnetohydrodynamic models and a new, fully time-dependent thermodynamic magnetohydrodynamic simulation of the global corona. The maps are…

Solar and Stellar Astrophysics · Physics 2023-06-22 Emily I. Mason , Roberto Lionello , Cooper Downs , Jon A. Linker , Ronald M. Caplan

For the first time, we demonstrate how an MHD avalanche might occur in a multi-threaded coronal loop. Considering 23 non-potential magnetic threads within a loop, we use 3D MHD simulations to show that only one thread needs to be unstable…

Solar and Stellar Astrophysics · Physics 2016-01-27 A. W. Hood , P. J. Cargill , P. K. Browning , K. V. Tam

A recent third-order, essentially non-oscillatory central scheme to advance the equations of single-fluid magnetohydrodynamics (MHD) in time has been implemented into a new numerical code. This code operates on a 3-D Cartesian,…

Solar and Stellar Astrophysics · Physics 2012-04-18 Jens Kleimann , Andreas Kopp , Horst Fichtner , Rainer Grauer

This work analyzes the Hall magnetohydrodynamics (HMHD) and magnetohydrodynamics (MHD) numerical simulations of a flaring solar active region as a testbed while idealizing the coronal Alfv\'en speed to be of two orders of magnitude lesser.…

Solar and Stellar Astrophysics · Physics 2022-02-16 Kamlesh Bora , Ramit Bhattacharyya , Avijeet Prasad , Bhuwan Joshi , Qiang Hu

Context: The location of coronal heating in magnetic loops has been the subject of a long-lasting controversy: does it occur mostly at the loop footpoints, at the top, is it random, or is the average profile uniform? Aims: We try to address…

Astrophysics · Physics 2009-11-13 E. Buchlin , P. J. Cargill , S. J. Bradshaw , M. Velli

Magnetic energy is required to heat the corona, the outer atmosphere of the Sun, to millions of degrees. We study the nature of the magnetic energy source that is probably responsible for the brightening of coronal loops driven by…

Solar and Stellar Astrophysics · Physics 2018-07-25 L. P. Chitta , H. Peter , S. K. Solanki

Nanoflares are impulsive energy releases by magnetic reconnection in the braided coronal magnetic field, which is a potential mechanism for heating the corona. However, there are still sporadic observations of the interchange of braiding…

Solar and Stellar Astrophysics · Physics 2023-11-01 Y. Bi , J. J. Yang , Y. Qin , Z. P. Qiang , J. C. Hong , B. Yang , Z. Xu , H. Liu , K. F. Ji

Nanoflares in quiet-Sun regions during solar cycle 24 are studied with the best available plasma diagnostics to derive their energy distribution and contribution to coronal heating during different levels of solar activity. Extreme…

Solar and Stellar Astrophysics · Physics 2022-05-25 Stefan Purkhart , Astrid M. Veronig

Determining the mechanisms responsible for the heating of the coronal plasma and maintaining and accelerating the solar wind are long standing goals in solar physics. There is a clear need to constrain the energy, mass and momentum flux…

Solar and Stellar Astrophysics · Physics 2016-11-21 R. J. Morton , E. Scullion , D. S. Bloomfield , J. A. McLaughlin , S. Regnier , S. W. McIntosh , S. Tomczyk , P. Young

The physical properties responsible for the formation and evolution of the corona and heliosphere are still not completely understood. 3D MHD global modeling is a powerful tool to investigate all the possible candidate processes. To fully…