Results
Title

Wave-like Formation of Hot Loop Arcades.

Authors

Reva, A.; Shestov, S.; Zimovets, I.; Bogachev, S.; Kuzin, S.

Abstract

We present observations of hot arcades made with the Mg xii spectroheliograph onboard the CORONAS-F mission, which provides monochromatic images of hot plasma in the Mg xii 8.42 Å resonance line. The arcades were observed to form above the polarity inversion line between active regions NOAA 09847 and 09848 at four successive episodes: at 09:18, 14:13, and 22:28 UT on 28 February 2002, and at 00:40 UT on 1 March 2002. The evolution of the arcades can be described as: a) a small flare (precursor) appeared near the edge of the still invisible arcade, b) the arcade brightened in a wave-like manner - closer loops brightened earlier, and c) the arcade intensity gradually decreased in ${\approx}\,1~\mbox{h}$. The estimated wave speed was ${\approx}\,700~\mbox{km}\,\mbox{s}^{-1}$, and the distance between the hot loops was ${\approx}\,50~\mbox{Mm}$. The arcades formed without visible changes in their magnetic structure. The arcades were probably heated up by the instabilities of the current sheet above the arcade, which were caused by a magnetohydrodynamic wave excited by the precursor.

Subjects

SPECTROHELIOGRAPH; MAGNESIUM; WAVE analysis; HIGH temperature plasmas; UMPOLUNG; MAGNETIC structure

Publication

Solar Physics, 2015, Vol 290, Issue 10, p2909

ISSN

0038-0938

Publication type

Academic Journal

DOI

10.1007/s11207-015-0769-x