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Title: Observations of supra-arcade fans: instabilities at the head of reconnection jets

Abstract

Supra-arcade fans are bright, irregular regions of emission that develop during eruptive flares above flare arcades. The underlying flare arcades are thought to be a consequence of magnetic reconnection along a current sheet in the corona. At the same time, theory predicts plasma jets from the reconnection sites which are extremely difficult to observe directly because of their low densities. It has been suggested that the dark supra-arcade downflows (SADs) seen falling through supra-arcade fans may be low-density jet plasma. The head of a low-density jet directed toward higher-density plasma would be Rayleigh-Taylor unstable, and lead to the development of rapidly growing low- and high-density fingers along the interface. Using Solar Dynamics Observatory/Atmospheric Imaging Assembly 131 Å images, we show details of SADs seen from three different orientations with respect to the flare arcade and current sheet, and highlight features that have been previously unexplained, such as the splitting of SADs at their heads, but are a natural consequence of instabilities above the arcade. Comparison with three-dimensional magnetohydrodynamic simulations suggests that SADs are the result of secondary instabilities of the Rayleigh-Taylor type in the exhaust of reconnection jets.

Authors:
; ;  [1];
  1. Max Planck Institute for Solar System Research, D-37077 Göttingen (Germany)
Publication Date:
OSTI Identifier:
22369967
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 796; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; DENSITY; EMISSION; INSTABILITY; MAGNETIC RECONNECTION; MAGNETOHYDRODYNAMICS; PLASMA DENSITY; PLASMA JETS; RAYLEIGH-TAYLOR INSTABILITY; SIMULATION; SUN; THREE-DIMENSIONAL CALCULATIONS

Citation Formats

Innes, D. E., Guo, L. -J., Schmit, D., Bhattacharjee, A., and Huang, Y.-M., E-mail: innes@mps.mpg.de. Observations of supra-arcade fans: instabilities at the head of reconnection jets. United States: N. p., 2014. Web. doi:10.1088/0004-637X/796/1/27.
Innes, D. E., Guo, L. -J., Schmit, D., Bhattacharjee, A., & Huang, Y.-M., E-mail: innes@mps.mpg.de. Observations of supra-arcade fans: instabilities at the head of reconnection jets. United States. https://doi.org/10.1088/0004-637X/796/1/27
Innes, D. E., Guo, L. -J., Schmit, D., Bhattacharjee, A., and Huang, Y.-M., E-mail: innes@mps.mpg.de. 2014. "Observations of supra-arcade fans: instabilities at the head of reconnection jets". United States. https://doi.org/10.1088/0004-637X/796/1/27.
@article{osti_22369967,
title = {Observations of supra-arcade fans: instabilities at the head of reconnection jets},
author = {Innes, D. E. and Guo, L. -J. and Schmit, D. and Bhattacharjee, A. and Huang, Y.-M., E-mail: innes@mps.mpg.de},
abstractNote = {Supra-arcade fans are bright, irregular regions of emission that develop during eruptive flares above flare arcades. The underlying flare arcades are thought to be a consequence of magnetic reconnection along a current sheet in the corona. At the same time, theory predicts plasma jets from the reconnection sites which are extremely difficult to observe directly because of their low densities. It has been suggested that the dark supra-arcade downflows (SADs) seen falling through supra-arcade fans may be low-density jet plasma. The head of a low-density jet directed toward higher-density plasma would be Rayleigh-Taylor unstable, and lead to the development of rapidly growing low- and high-density fingers along the interface. Using Solar Dynamics Observatory/Atmospheric Imaging Assembly 131 Å images, we show details of SADs seen from three different orientations with respect to the flare arcade and current sheet, and highlight features that have been previously unexplained, such as the splitting of SADs at their heads, but are a natural consequence of instabilities above the arcade. Comparison with three-dimensional magnetohydrodynamic simulations suggests that SADs are the result of secondary instabilities of the Rayleigh-Taylor type in the exhaust of reconnection jets.},
doi = {10.1088/0004-637X/796/1/27},
url = {https://www.osti.gov/biblio/22369967}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 796,
place = {United States},
year = {Thu Nov 20 00:00:00 EST 2014},
month = {Thu Nov 20 00:00:00 EST 2014}
}