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We investigate non-ideal magnetohydrodynamical (MHD) effects in the chromosphere on the solar wind by performing MHD simulations for Alfv\'en-wave driven winds with explicitly including Ohmic and ambipolar diffusion. We find that MHD waves…

Solar and Stellar Astrophysics · Physics 2024-05-09 Masato Matsuoka , Takeru K. Suzuki , Takato Tokuno , Kensuke Kakiuchi

We numerically investigate the excitation and temporal evolution of oscillations in a two-dimensional coronal arcade by including the three-dimensional propagation of perturbations. The time evolution of impulsively generated perturbations…

Solar and Stellar Astrophysics · Physics 2015-05-18 S. Rial , I. Arregui , J. Terradas , R. Oliver , J. L. Ballester

Interactions between clouds and radiation are at the root of many difficulties in numerically predicting future weather and climate and in retrieving the state of the atmosphere from remote sensing observations. The large range of issues…

Although it is widely accepted that photospheric motions provide the energy source and that the magnetic field must play a key role in the process, the detailed mechanisms responsible for heating the Sun's corona and accelerating the solar…

Solar and Stellar Astrophysics · Physics 2016-01-12 Roberto Lionello , Marco Velli , Cooper Downs , Jon A. Linker , Zoran Mikić

The objective of this study is to develop a fully compressible magnetohydrodynamic solver for fast simulations of the global dynamo of the Sun using unstructured grids and GPUs. Accurate modeling of the Sun's convective layers is vital to…

Solar and Stellar Astrophysics · Physics 2025-02-26 Aidan Paoli , Chunlei Liang

The reconstruction of the solar spectral irradiance (SSI) on various time scales is essential for the understanding of the Earth's climate response to the SSI variability. The driver of the SSI variability is understood to be the intensity…

Solar and Stellar Astrophysics · Physics 2021-09-29 M. Haberreiter , S. Criscuoli , M. Rempel , T. M. D. Pereira

Magnetic field in the solar corona is usually extrapolated from photospheric vector magnetogram using a nonlinear force-free field (NLFFF) model. NLFFF extrapolation needs a considerable effort to be devoted for its numerical realization.…

Solar and Stellar Astrophysics · Physics 2015-06-04 Chaowei Jiang , Xueshang Feng

The Sun's magnetic field is a key driver in coronal heating and consequently solar wind acceleration. Remote measurement of the photosphere provides the magnetic surface boundary condition necessary for data-constrained 3D global coronal…

Solar and Stellar Astrophysics · Physics 2025-11-06 Caroline L. Evans , Cooper Downs , Donald Schmit

Context: Radiation-MHD simulations have become a standard tool to investigate the physics of solar and stellar atmospheres. Aims: The aim of this paper to present a method that allows efficient and accurate analysis of flows in such…

Solar and Stellar Astrophysics · Physics 2018-09-05 Jorrit Leenaarts

We present evidence that transition region red-shifts are naturally produced in episodically heated models where the average volumetric heating scale height lies between that of the chromospheric pressure scale height of 200 km and the…

Solar and Stellar Astrophysics · Physics 2015-05-18 Viggo H. Hansteen , Hirohisa Hara , Bart de Pontieu , Mats Carlsson

The efficacy of fast/slow MHD mode conversion in the surface layers of sunspots has been demonstrated over recent years using a number of modelling techniques, including ray theory, perturbation theory, differential eigensystem analysis,…

Astrophysics · Physics 2009-11-13 P. S. Cally , M. Goossens

The nanoflare paradigm of coronal heating has proven extremely promising for explaining the presence of hot, multi-million degree loops in the solar corona. In this paradigm, localized heating events supply enough energy to heat the solar…

Solar and Stellar Astrophysics · Physics 2020-09-02 Kalman J. Knizhnik , Will T. Barnes , Jeffrey W. Reep , Vadim M. Uritsky

Nearly all energy generated by fusion in the solar core is ultimately radiated away into space in the solar atmosphere, while the remaining energy is carried away in the form of neutrinos. The exchange of energy between the solar gas and…

Solar and Stellar Astrophysics · Physics 2020-04-01 Jorrit Leenaarts

The spatial properties of the solar magnetic field are crucial to decoding the physical processes in the solar interior and their interplanetary effects. However, observations from older instruments, such as the Michelson Doppler Imager…

Solar and Stellar Astrophysics · Physics 2025-06-11 Francesco Pio Ramunno , Paolo Massa , Vitaliy Kinakh , Brandon Panos , André Csillaghy , Slava Voloshynovskiy

The solar surface and atmosphere are highly dynamic plasma environments, which evolve over a wide range of temporal and spatial scales. Large-scale eruptions, such as coronal mass ejections, can be accelerated to millions of kilometres per…

We present a newly developed approach to solar coronal magnetic field extrapolation from vector magnetograms, based on the Principle of Minimum Dissipation Rate (MDR). The MDR system was derived from a variational problem that is more…

Astrophysics · Physics 2009-11-13 Q. Hu , B. Dasgupta , D. P. Choudhary , J. Büchner

We present a three-dimensional model of rotating convection combined with a simplified corona in spherical coordinates. The motions in the convection zone generate a large-scale magnetic field that gets sporadically ejected into the outer…

Solar and Stellar Astrophysics · Physics 2012-07-17 Jörn Warnecke , Petri J. Käpylä , Maarit. J. Mantere , Axel Brandenburg

The dynamic process of coronal mass ejections (CMEs) in the heliosphere provides us the key information for evaluating CMEs' geo-effectiveness and improving the accurate prediction of CME induced Shock Arrival Time (SAT) at the Earth. We…

Solar and Stellar Astrophysics · Physics 2015-01-09 Fang Shen , Chenglong Shen , Jie Zhang , Phillip Hess , Yuming Wang , Xueshang Feng , Hongze Cheng , Yi Yang

We present 3-D hydrodynamical simulations of core convection with a stably stratified envelope of a \unit{25}{\Msun} star in the early phase of the main-sequence. We use the explicit gas-dynamics code \code{PPMstar} which tracks two fluids…

Solar and Stellar Astrophysics · Physics 2024-08-13 Huaqing Mao , Paul Woodward , Falk Herwig , Pavel A. Denissenkov , Simon Blouin , William Thompson , Benjamin McDermott

Long-time high-resolution simulations of the dynamics of a coronal loop in cartesian geometry are carried out, within the framework of reduced magnetohydrodynamics (RMHD), to understand coronal heating driven by motion of field lines…

Astrophysics · Physics 2008-11-26 A. F. Rappazzo , M. Velli , G. Einaudi , R. B. Dahlburg
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