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We introduce two new methods that are designed to improve the realism and utility of large, active region-scale 3D MHD models of the solar atmosphere. We apply these methods to RADMHD, a code capable of modeling the Sun's upper convection…

Solar and Stellar Astrophysics · Physics 2010-05-06 William P. Abbett , George H. Fisher

The solar magnetic fields emerging from the photosphere into the chromosphere and corona are comprised of a combination of "closed" and "open" fields. The closed magnetic field lines are defined as those having both ends rooted in the solar…

Solar and Stellar Astrophysics · Physics 2023-04-18 C. Nick Arge , Andrew Leisner , Samantha Wallace , Carl J. Henney

We explore the capabilities of time-dependent (TD) magnetohydrodynamics (MHD) solar wind simulations with the coupled WSA model of the solar corona and GAMERA model of the inner heliosphere. We compare TD with steady state (SS) simulations…

Solar and Stellar Astrophysics · Physics 2025-09-26 Evangelia Samara , Elena Provornikova , C. Nick Arge , Andrew McCubbin , Viacheslav G. Merkin

The quality of today's research is often tightly limited to the available computing power and scalability of codes to many processors. For example, tackling the problem of heating the solar corona requires a most realistic description of…

Solar and Stellar Astrophysics · Physics 2019-08-26 Philippe-A. Bourdin

With current observational methods it is not possible to directly measure the magnetic field in the solar corona with sufficient accuracy. Therefore, coronal magnetic field models have to rely on extrapolation methods using photospheric…

Solar and Stellar Astrophysics · Physics 2025-04-24 Lilli Nadol , Thomas Neukirch

We describe observations of a white-light flare (SOL2011-02-24T07:35:00, M3.5) close to the limb of the Sun, from which we obtain estimates of the heights of the optical continuum sources and those of the associated hard X-ray sources.For…

Force-free extrapolations are widely used to study the magnetic field in the solar corona based on surface measurements. The extrapolations assume that the ratio of internal energy of the plasma to magnetic energy, the plasma-beta is…

Solar and Stellar Astrophysics · Physics 2015-11-25 H. Peter , J. Warnecke , L. P. Chitta , R. H. Cameron

We argue that a variety of solar data suggest that the activity-cycle timescale variability of the total irradiance, is produced by structural adjustments of the solar interior. Assuming these adjustments are induced by variations of…

Astrophysics · Physics 2009-10-31 L. H. Li , S. Sofia

We present a novel magnetohydrostatic numerical model that solves directly for the force-balanced magnetic field in the solar corona. This model is constructed with Radial Basis Function Finite Differences (RBF-FD), specifically 3D…

Solar and Stellar Astrophysics · Physics 2022-05-11 Nathaniel H. Mathews , Natasha Flyer , Sarah E. Gibson

The origins of the hot solar corona and the supersonically expanding solar wind are still the subject of debate. A key obstacle in the way of producing realistic simulations of the Sun-heliosphere system is the lack of a physically…

Solar and Stellar Astrophysics · Physics 2014-11-20 Steven R. Cranmer

We recently proposed a method to calculate the relative magnetic helicity in a finite volume for a given magnetic field which however required the flux to be balanced separately on all the sides of the considered volume. In order to allow…

Solar and Stellar Astrophysics · Physics 2018-05-30 Shangbin Yang , Joerg Buechner , Jan Skala , Hongqi Zhang

Solar wind back-mapping is a combination of ballistic mapping and magnetic mapping. By examining the different model ingredients that can affect the derived back-mapped position, we aim to provide a more precise estimate of the source…

Solar and Stellar Astrophysics · Physics 2025-02-12 Alexandros Koukras , Laurent Dolla , Rony Keppens

We present a careful assess of the forced field extrapolation using Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) magnetogram. The convergence property is checked by several metrics. The extrapolated field lines…

Solar and Stellar Astrophysics · Physics 2017-03-22 Xiaoshuai Zhu , Huaning Wang , Zhanle Du , Han He

The coupling between small and large scale structures and processes on the Sun and in the heliosphere is important in the relation to the global magnetic configuration. Thin heliospheric current sheets play the leading role in this respect.…

Solar and Stellar Astrophysics · Physics 2012-12-24 Igor Veselovsky , Olga Panasenco

We examine the temporal changes in both solar polar magnetic field (PMF) at latitudes $\ge$ $45^{\circ}$ and heliospheric magnetic field (HMF) at 1 AU during solar cycles 21--24 with emphasis on the recent activity changes after July 2015,…

Solar and Stellar Astrophysics · Physics 2020-08-05 Susanta Kumar Bisoi , P. Janardhan , S. Ananthakrishnan

The adopted WSA model embedded in EUHFORIA (EUropean Heliospheric FORecasting Information Asset) is compared to EUV observations. According to the standard paradigm coronal holes are sources of open flux thus we use remote sensing EUV…

Solar and Stellar Astrophysics · Physics 2020-01-08 Eleanna Asvestari , Stephan G. Heinemann , Mannuela Temmer , Jens Pomoell , Emilia Kilpua , Jasmina Magdalenic , Stefaan Poedts

Global magnetohydrodynamic (MHD) models play an important role in the infrastructure of space weather forecasting. Validating such models commonly utilizes in situ solar wind measurements made near the orbit of the Earth. The purpose of…

Solar and Stellar Astrophysics · Physics 2024-10-31 Chin-Chun Wu , Kan Liou , Brian E. Wood , Y. M. Wang

Estimating Alfven speeds is of interest in modelling the solar corona, studying the coronal heating problem and understanding the initiation and propagation of coronal mass ejections (CMEs). We assume here that the corona is in a…

Astrophysics · Physics 2009-11-13 S. Regnier , E. R. Priest , A. W. Hood

Three-dimensional (3D) magnetic field in the solar atmosphere provides crucial information to understand the explosive phenomenon such as solar flares and coronal mass ejections. Since it is still hard that we determine the 3D magnetic…

Solar and Stellar Astrophysics · Physics 2026-01-07 Daiki Yamasaki , Takahiro Miyoshi , Satoshi Inoue

The dynamics of the solar wind depends intrinsically on the structure of the global solar magnetic field, which undergoes fundamental changes over the 11-yr solar cycle. For instance, the wind terminal velocity is thought to be…

Solar and Stellar Astrophysics · Physics 2017-11-29 Victor Réville , Allan Sacha Brun