Fine structures of solar radio type III bursts and their possible relationship with coronal density turbulence

Chen, X., Kontar, E. P. , Yu, S., Yan, Y., Huang, J. and Tan, B. (2018) Fine structures of solar radio type III bursts and their possible relationship with coronal density turbulence. Astrophysical Journal, 856(1), 73. (doi:10.3847/1538-4357/aaa9bf)

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Abstract

Solar radio type III bursts are believed to be the most sensitive signatures of near-relativistic electron beam propagation in the corona. A solar radio type IIIb-III pair burst with fine frequency structures, observed by the Low Frequency Array (LOFAR) with high temporal (~10 ms) and spectral (12.5 kHz) resolutions at 30–80 MHz, is presented. The observations show that the type III burst consists of many striae, which have a frequency scale of about 0.1 MHz in both the fundamental (plasma) and the harmonic (double plasma) emission. We investigate the effects of background density fluctuations based on the observation of striae structure to estimate the density perturbation in the solar corona. It is found that the spectral index of the density fluctuation spectrum is about −1.7, and the characteristic spatial scale of the density perturbation is around 700 km. This spectral index is very close to a Kolmogorov turbulence spectral index of −5/3, consistent with a turbulent cascade. This fact indicates that the coronal turbulence may play the important role of modulating the time structures of solar radio type III bursts, and the fine structure of radio type III bursts could provide a useful and unique tool to diagnose the turbulence in the solar corona.

Item Type:Articles
Keywords:Space and planetary science, astronomy and astrophysics
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Chen, Ms Xingyao and Kontar, Professor Eduard
Authors: Chen, X., Kontar, E. P., Yu, S., Yan, Y., Huang, J., and Tan, B.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Astrophysical Journal
Publisher:IOP Publishing
ISSN:0004-637X
ISSN (Online):1538-4357
Published Online:27 March 2018
Copyright Holders:Copyright © 2018 The American Astronomical Society
First Published:First published in Astrophysical Journal 856:73
Publisher Policy:Reproduced under a Creative Commons License
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
631581Consolidated grant in solar and astrophysical plasmasLyndsay FletcherScience & Technology Facilities Council (STFC)ST/L000741/1S&E P&A - PHYSICS & ASTRONOMY

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