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Title: SOLAR RADIO BURSTS WITH SPECTRAL FINE STRUCTURES IN PREFLARES

Good observations of preflare activities are important for us to understand the origin and triggering mechanism of solar flares, and to predict the occurrence of solar flares. This work presents the characteristics of microwave spectral fine structures as preflare activities of four solar flares observed by the Ondřejov radio spectrograph in the frequency range of 0.8-2.0 GHz. We found that these microwave bursts which occurred 1-4 minutes before the onset of flares have spectral fine structures with relatively weak intensities and very short timescales. They include microwave quasi-periodic pulsations with very short periods of 0.1-0.3 s and dot bursts with millisecond timescales and narrow frequency bandwidths. Accompanying these microwave bursts are filament motions, plasma ejection or loop brightening in the EUV imaging observations, and non-thermal hard X-ray emission enhancements observed by RHESSI. These facts may reveal certain independent, non-thermal energy releasing processes and particle acceleration before the onset of solar flares. They may help us to understand the nature of solar flares and to predict their occurrence.
Authors:
; ; ;  [1] ; ;  [2] ;  [3]
  1. Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Chaoyang District, Beijing 100012 (China)
  2. Astronomical Institute of the Academy of Sciences of the Czech Republic, 25165 Ondřejov (Czech Republic)
  3. SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)
Publication Date:
OSTI Identifier:
22364547
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; FILAMENTS; FINE STRUCTURE; GHZ RANGE; HARD X RADIATION; MICROWAVE RADIATION; ORIGIN; PERIODICITY; PLASMA; PULSATIONS; SOLAR FLARES; SOLAR RADIO BURSTS; SUN