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Title: Double Arc Instability in the Solar Corona

Abstract

The stability of the magnetic field in the solar corona is important for understanding the causes of solar eruptions. Although various scenarios have been suggested to date, the tether-cutting reconnection scenario proposed by Moore et al. is one of the widely accepted models to explain the onset process of solar eruptions. Although the tether-cutting reconnection scenario proposes that the sigmoidal field formed by internal reconnection is the magnetic field in the pre-eruptive state, the stability of the sigmoidal field has not yet been investigated quantitatively. In this paper, in order to elucidate the stability problem of the pre-eruptive state, we developed a simple numerical analysis in which the sigmoidal field is modeled by a double arc electric current loop and its stability is analyzed. As a result, we found that the double arc loop is more easily destabilized than the axisymmetric torus, and it becomes unstable even if the external field does not decay with altitude, which is in contrast to the axisymmetric torus instability. This suggests that tether-cutting reconnection may well work as the onset mechanism of solar eruptions, and if so, the critical condition for eruption under a certain geometry may be determined by a new type ofmore » instability rather than by the torus instability. Based on them, we propose a new type of instability called double arc instability (DAI). We discuss the critical conditions for DAI and derive a new parameter κ , defined as the product of the magnetic twist and the normalized flux of the tether-cutting reconnection.« less

Authors:
;  [1]
  1. Institute for Space-Earth Environmental Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601 Japan (Japan)
Publication Date:
OSTI Identifier:
22663413
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 843; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AXIAL SYMMETRY; ELECTRIC ARCS; ERUPTION; INSTABILITY; MAGNETIC FIELDS; MASS; NUMERICAL ANALYSIS; SOLAR CORONA; SOLAR FLARES; STABILITY; SUN

Citation Formats

Ishiguro, N., and Kusano, K., E-mail: n-ishiguro@isee.nagoya-u.ac.jp. Double Arc Instability in the Solar Corona. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA799B.
Ishiguro, N., & Kusano, K., E-mail: n-ishiguro@isee.nagoya-u.ac.jp. Double Arc Instability in the Solar Corona. United States. doi:10.3847/1538-4357/AA799B.
Ishiguro, N., and Kusano, K., E-mail: n-ishiguro@isee.nagoya-u.ac.jp. Mon . "Double Arc Instability in the Solar Corona". United States. doi:10.3847/1538-4357/AA799B.
@article{osti_22663413,
title = {Double Arc Instability in the Solar Corona},
author = {Ishiguro, N. and Kusano, K., E-mail: n-ishiguro@isee.nagoya-u.ac.jp},
abstractNote = {The stability of the magnetic field in the solar corona is important for understanding the causes of solar eruptions. Although various scenarios have been suggested to date, the tether-cutting reconnection scenario proposed by Moore et al. is one of the widely accepted models to explain the onset process of solar eruptions. Although the tether-cutting reconnection scenario proposes that the sigmoidal field formed by internal reconnection is the magnetic field in the pre-eruptive state, the stability of the sigmoidal field has not yet been investigated quantitatively. In this paper, in order to elucidate the stability problem of the pre-eruptive state, we developed a simple numerical analysis in which the sigmoidal field is modeled by a double arc electric current loop and its stability is analyzed. As a result, we found that the double arc loop is more easily destabilized than the axisymmetric torus, and it becomes unstable even if the external field does not decay with altitude, which is in contrast to the axisymmetric torus instability. This suggests that tether-cutting reconnection may well work as the onset mechanism of solar eruptions, and if so, the critical condition for eruption under a certain geometry may be determined by a new type of instability rather than by the torus instability. Based on them, we propose a new type of instability called double arc instability (DAI). We discuss the critical conditions for DAI and derive a new parameter κ , defined as the product of the magnetic twist and the normalized flux of the tether-cutting reconnection.},
doi = {10.3847/1538-4357/AA799B},
journal = {Astrophysical Journal},
number = 2,
volume = 843,
place = {United States},
year = {Mon Jul 10 00:00:00 EDT 2017},
month = {Mon Jul 10 00:00:00 EDT 2017}
}