TY - JOUR
T1 - On the Source Position and Duration of a Solar Type III Radio Burst Observed by LOFAR
AU - Zhang, Pei Jin
AU - Yu, Si Jie
AU - Kontar, Eduard P.
AU - Wang, Chuan Bing
N1 - Funding Information:
PeiJin Zhang SiJie Yu Eduard P. Kontar ChuanBing Wang PeiJin Zhang SiJie Yu Eduard P. Kontar ChuanBing Wang CAS Key Laboratory of Geospace Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China CAS Center for the Excellence in Comparative Planetology, Hefei, Anhui 230026, People's Republic of China New Jersey Institute of Technology, Newark, NJ 07102, USA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK PeiJin Zhang, SiJie Yu, Eduard P. Kontar and ChuanBing Wang 2019-11-10 2019-11-08 13:27:48 cgi/release: Article released bin/incoming: New from .zip National Nature Science Foundation of China 41574167 41174123 NASA NNX17AB82G National Science Foundation (NSF) AGS-1654382 Science and Technology Facilities Council (STFC) ST/P000533/1 yes 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 0.42 c , 0.25 c , and 0.16 c , 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. � 2019. The American Astronomical Society. All rights reserved. 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Publisher Copyright:
© 2019 The American Astronomical Society. All rights reserved.
PY - 2019/11/10
Y1 - 2019/11/10
N2 - 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.
AB - 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.
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U2 - 10.3847/1538-4357/ab458f
DO - 10.3847/1538-4357/ab458f
M3 - Article
AN - SCOPUS:85075319890
SN - 0004-637X
VL - 885
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 140
ER -