Kumar, Pankaj, Nakariakov, V. M. (Valery M.) and Cho, Kyung-Suk (2017) Quasi-periodic radio bursts associated with fast-mode waves near a magnetic null point. The Astrophysical Journal, 844 (2). 149. doi:10.3847/1538-4357/aa7d53

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Abstract

This paper presents an observation of quasi-periodic rapidly propagating waves observed in the Atmospheric Image Assembly (AIA) 171/193 Å channels during the impulsive phase of an M1.9 flare that occurred on 2012 May 7. The instant period was found to decrease from 240 to 120 s, and the speed of the wavefronts was in the range of ~664–1416 km s−1. Almost simultaneously, quasi-periodic bursts with similar instant periods, ~70 and ~140 s, occur in the microwave emission and in decimetric type IV and type III radio bursts, and in the soft X-ray emission. The magnetic field configuration of the flare site was consistent with a breakout topology, i.e., a quadrupolar field along with a magnetic null point. The quasi-periodic rapidly propagating wavefronts of the EUV emission are interpreted as a fast magnetoacoustic wave train. The observations suggest that the fast-mode waves are generated during the quasi-periodic magnetic reconnection in the cusp region above the flare arcade loops. For the first time, we provide evidence of a tadpole wavelet signature at about 70–140 s in decimetric (245/610 MHz) radio bursts, along with the direct observation of a coronal fast-mode wave train in EUV. In addition, at AIA 131/193 Å we observed quasi-periodic EUV disturbances with periods of 95 and 240 s propagating downward at apparent speeds of 172–273 km s−1. The nature of these downward propagating disturbances is not revealed, but they could be connected to magnetoacoustic waves or periodically shrinking loops.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Solar flares, Sun -- Corona, Solar oscillations, Solar radiation, Solar radio bursts
Journal or Publication Title:	The Astrophysical Journal
Publisher:	Institute of Physics Publishing, Inc.
ISSN:	0004-637X
Official Date:	2 August 2017
Dates:	Date Event 2 August 2017 Published 29 June 2017 Accepted
Date of first compliant deposit:	17 January 2018
Volume:	844
Number:	2
Article Number:	149
DOI:	10.3847/1538-4357/aa7d53
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
RIOXX Funder/Project Grant:	Project/Grant ID RIOXX Funder Name Funder ID Development of Korea Space Weather Center Korea Astronomy and Space Science Institute http://dx.doi.org/10.13039/501100003717 FA 2386-14-1-4078 U.S. Air Force http://dx.doi.org/10.13039/100006831 Planetary system research for space exploration Korea Astronomy and Space Science Institute http://dx.doi.org/10.13039/501100003717 SeismoSun Research Project No. 321141 FP7 Ideas: European Research Council http://dx.doi.org/10.13039/100011199 BK21 plus program National Research Foundation of Korea http://dx.doi.org/10.13039/501100003725 Postdoctoral Program National Aeronautics and Space Administration http://dx.doi.org/10.13039/100000104
Is Part Of:	European Research Council under the SeismoSun Research Project No. 321141 0000-0001-6423-8286

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