Solar radio bursts with spectral fine structures in preflares

0444992 - ASÚ 2016 RIV US eng J - Journal Article
Zhang, J. - Tan, B.-L. - Karlický, Marian - Mészárosová, Hana - Huang, J. - Tan, C.M. - Simoes, P.J.A.
Solar radio bursts with spectral fine structures in preflares.
Astrophysical Journal. Roč. 799, č. 1 (2015), 30/1-30/13. ISSN 0004-637X. E-ISSN 1538-4357
Institutional support: RVO:67985815
Keywords : Sun corona * Sun flares * radio radiation
Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics
Impact factor: 5.909, year: 2015

This work presents the characteristics of microwave spectral fine structures as preflare activities of four solar flares observed by the Ond. rejov 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.
Permanent Link: http://hdl.handle.net/11104/0247450