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We present the first results of three-dimensional (3D) numerical magnetohydrodynamic (MHD) simulations of the onset of magnetic reconnection via the tearing instability in dynamically thinning current sheets in the solar corona. In all our…

Solar and Stellar Astrophysics · Physics 2024-06-10 James Leake , Lars Daldorff , James Klimchuk

We investigate the dynamical evolution of magnetic fields in closed regions of solar and stellar coronae. To understand under which conditions current sheets form, we examine dissipative and ideal reduced magnetohydrodynamic models in…

Solar and Stellar Astrophysics · Physics 2013-07-30 A. F. Rappazzo , E. N. Parker

Kinetic-scale current sheets observed in the solar wind are frequently approximately force-free despite the fact that their plasma $\beta$ is of the order of one. In-situ measurements have recently shown that plasma density and temperature…

Space Physics · Physics 2020-03-18 T. Neukirch , I. Y. Vasko , A. V. Artemyev , O. Allanson

Current sheets are essential for energy dissipation in the solar corona, in particular by enabling magnetic reconnection. Unfortunately, sufficiently thin current sheets cannot be resolved observationally and the theory of their formation…

Astrophysics · Physics 2025-07-21 Joerg Buechner

The boundary conditions for the ideal MHD equations on a plane dis- continuity surface are investigated. It is shown that, for a given mass flux through a discontinuity, its type depends only on the relation between inclina- tion angles of…

Plasma Physics · Physics 2016-01-20 L. S. Ledentsov , B. V. Somov

Context. Photospheric motions shuffle the footpoints of the strong axial magnetic field that threads coronal loops giving rise to turbulent nonlinear dynamics characterized by the continuous formation and dissipation of field-aligned…

Solar and Stellar Astrophysics · Physics 2012-08-14 R. B. Dahlburg , G. Einaudi , A. F. Rappazzo , M. Velli

The magnetic topology and field line random walk properties of a nanoflare-heated and magnetically confined corona are investigated in the reduced magnetohydrodynamic regime. Field lines originating from current sheets form coherent…

Solar and Stellar Astrophysics · Physics 2017-07-27 A. F. Rappazzo , W. H. Matthaeus , D. Ruffolo , M. Velli , S. Servidio

The thickness of current sheets is extremely important, especially as it relates to the onset of fast magnetic reconnection. Onset determines how much magnetic free energy can build up in a field before it is explosively released. This has…

Solar and Stellar Astrophysics · Physics 2023-07-27 James A. Klimchuk , James E. Leake , Lars K. S. Daldorff , Craig D. Johnston

The Parker or field line tangling model of coronal heating is studied comprehensively via long-time high-resolution simulations of the dynamics of a coronal loop in cartesian geometry within the framework of reduced magnetohydrodynamics…

Astrophysics · Physics 2009-12-06 A. F. Rappazzo , M. Velli , G. Einaudi , R. B. Dahlburg

Recent radioastronomical observations of Faraday rotation in the solar corona can be interpreted as evidence for coronal currents, with values as large as $2.5 \times 10^9$ Amperes (Spangler 2007). These estimates of currents are used to…

Astrophysics · Physics 2020-01-29 Steven R. Spangler

The dynamics of magnetic fields in closed regions of solar and stellar coronae are investigated with a reduced magnetohydrodynamic (MHD) model in the framework of Parker scenario for coronal heating. A novel analysis of reduced MHD…

Solar and Stellar Astrophysics · Physics 2015-12-04 A. F. Rappazzo

Evidence for inhomogeneous heating in the interplanetary plasma near current sheets dynamically generated by magnetohydrodynamic (MHD) turbulence is obtained using measurements from the ACE spacecraft. These coherent structures only…

Space Physics · Physics 2013-12-04 K. T. Osman , W. H. Matthaeus , M. Wan , A. F. Rappazzo

Recent results of numerical magnetohydrodynamic simulations suggest that in collisionless space plasmas turbulence can spontaneously generate thin current sheets. These coherent structures can partially explain intermittency and the…

In this paper, we study the energy conversion and spectra in a corona current sheet by 2.5-dimensional MHD numerical simulations. Numerical results show that many Petschek-like fine structures with slow-mode shocks mediated by plasmoid…

Solar and Stellar Astrophysics · Physics 2015-12-29 Lei Ni , Jun Lin , Zhixing Mei , Yan Li

Advanced 3D radiative MHD simulations now reproduce many properties of the outer solar atmosphere. When including a domain from the convection zone into the corona, a hot chromosphere and corona are self-consistently maintained. Here we…

Solar and Stellar Astrophysics · Physics 2015-10-07 Viggo Hansteen , Nuno Guerreiro , Bart De Pontieu , Mats Carlsson

The nature and detailed properties of the heating of the million-degree solar corona are important issues that are still largely unresolved. Nanoflare heating might be dominant in active regions and quiet Sun, although direct signatures of…

Combined tearing-thermal evolution plays an important role in the disruption of current sheets, and formation of cool condensations within the solar atmosphere. However, this has received limited attention to date. We numerically explore a…

Solar and Stellar Astrophysics · Physics 2023-10-18 Samrat Sen , Jack Jenkins , Rony Keppens

We present an ab initio approach to the solar coronal heating problem by modelling a small part of the solar corona in a computational box using a 3D MHD code including realistic physics. The observed solar granular velocity pattern and its…

Astrophysics · Physics 2009-11-10 B. V. Gudiksen , Å. Nordlund

We investigate the spatial and temporal evolution of the heating of the corona of a cool star such as our Sun in a three-dimensional magneto-hydrodynamic (3D MHD) model. We solve the 3D MHD problem numerically in a box representing part of…

Space Physics · Physics 2015-05-27 Sven Bingert , Hardi Peter
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