Relative alpha in the magnetohydrodynamics with open magnetic field boundary and its application to the solar eruption

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F25%3A00617427" target="_blank" >RIV/67985815:_____/25:00617427 - isvavai.cz</a>

Result on the web

<a href="https://hdl.handle.net/11104/0365434" target="_blank" >https://hdl.handle.net/11104/0365434</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3847/1538-4357/ada278" target="_blank" >10.3847/1538-4357/ada278</a>

Result language

angličtina

Original language name

Relative alpha in the magnetohydrodynamics with open magnetic field boundary and its application to the solar eruption

Original language description

An instability criterion in the magnetohydrodynamics (MHD) with the open boundary of a magnetic field is proposed in this paper. We use a series of linear force-free extrapolation fields, in which the normal part of the magnetic field is fixed, to obtain the linear fitting coefficient called relative alpha by using the cojoined value of magnetic free energy and magnetic flux at the open boundary (Ef Phi 2) and the square of relative magnetic helicity ( HR2 ). We calculate this coefficient of the magnetic field above active regions NOAA 8210 and NOAA 11429 obtained by the photospheric-data-driven MHD model. It is found that the fitting coefficient is a good proxy of the criterion to indicate the occurrence of instability after which the magnetic reconnection happens and causes the fast release of magnetic energy. We also applied this method to the continuous evolution of the three-dimensional magnetic field of NOAA 11158 based on the measurement of the photospheric vector magnetic field of Solar Dynamics Observatory/Helioseismic and Magnetic Imager by the nonlinear force-free extrapolation method. The calculated coefficient when the major flare happened based on the extrapolation data is very close to the expected ones, which perfectly reflects the occurrence of instability, and the difference is even less than 7%. This relative alpha is very helpful to evaluate how far it is from the instability in the MHD and quantitatively estimate the occurrence of solar eruption in the space weather forecast.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

—

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Astrophysical Journal

ISSN

0004-637X

e-ISSN

1538-4357

Volume of the periodical

980

Issue of the periodical within the volume

2

Country of publishing house

GB - UNITED KINGDOM

Number of pages

5

Pages from-to

206

UT code for WoS article

001421901500001

EID of the result in the Scopus database

2-s2.0-85218236695