On the source position and duration of a solar type III radio burst observed by LOFAR

Zhang, P., Yu, S., Kontar, E. P. and Wang, C. (2019) On the source position and duration of a solar type III radio burst observed by LOFAR. Astrophysical Journal, 885(2), 140. (doi:10.3847/1538-4357/ab458f)

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Abstract

The flux of solar type III radio bursts have a time profile of rising and decay phases at a given frequency, which has been actively studied since the 1970s. Several factors that may influence the duration of a type III radio burst have been proposed. In this work, to study the dominant cause of the duration, we investigate the source positions of the front edge, the peak, and the tail edge in the dynamic spectrum of a single and clear type III radio burst. The duration of this type III burst at a given frequency is about 3 s for decameter wave. The beam-formed observations by the LOw-Frequency ARray are used, which can provide the radio source positions and the dynamic spectra at the same time. We find that, for this burst, the source positions of the front edge, the peak, and the tail edge split with each other spatially. The radial speed of the electrons exciting the front edge, the peak, and the tail edge is 0.42c, 0.25c, and 0.16c, respectively. We estimate the influences of the corona density fluctuation and the electron velocity dispersion on the duration, and the scattering effect by comparison with a few short-duration bursts from the same region. The analysis yields that, in the frequency range of 30–41 MHz, the electron velocity dispersion is the dominant factor that determines the time duration of type III radio bursts with long duration, while scattering may play an important role in the duration of short bursts.

Item Type:Articles
Additional Information:The research at USTC was supported by the National Nature Science Foundation of China (grant No. 41574167 and 41174123) and the Fundamental Research Funds for the Central Universities. S.Y. are supported by NSF grant AGS-1654382 awarded to the New Jersey Institute of Technology.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Kontar, Professor Eduard
Authors: Zhang, P., Yu, S., Kontar, E. P., and Wang, C.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Astrophysical Journal
Publisher:American Astronomical Society
ISSN:0004-637X
ISSN (Online):1538-4357
Published Online:08 November 2019
Copyright Holders:Copyright © 2019 The American Astronomical Society
First Published:First published in Astrophysical Journal 885(2):140
Publisher Policy:Reproduced in accordance with the publisher copyright policy
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
173869Consolidated Grant in Solar PhysicsLyndsay FletcherScience and Technology Facilities Council (STFC)ST/P000533/1P&S - Physics & Astronomy