MUSER Observations of an M8.7 Flare/CME Event without Coronal Dimming/EUV Waves
Abstract
The solar radio bursts are strongly related to solar activities. We present the solar radio bursts observed by the Mingantu Spectral Radioheliograph (MUSER) in China with 25 ms cadence and 25 MHz spectral resolution at 0.4-2.0 GHz and other multi-wavelengths imaging observations of an M8.7 flare/CME event in a circular active region on 2014 December 17. The solar radio spectral observations show a narrow band type III burst and some spikes overlaid on type IV radio continuum which presents oscillations of the non-thermal emission at a period of about 2-4 minutes during the flaring impulsive phase. An earth-directed CME occurred in this event. Coronal dimming & coronal EUV waves are usually associated with CMEs and as a signature for CME source regions (Cohen et al. 2009, Downs et al. 2012,Downs et al. 2015). Coronal dimming is also considered as a signature that could differentiate powerful flares that have CMEs from those that do not (Harra et al. 2016). However, for this impulsive M8.7 flare/CME event, coronal dimming and coronal EUV waves were not obvious or very weak. The imaging observations show that the radio bursts cover above the circular active region and are close to the flare ribbons in extreme ultraviolet (EUV) wavelengths. Additionally, the footpoints of the circular active region are expanding and oscillating at a period of about 3 minutes during preflare phase, which is very similar to the timescale of the non-thermal radio emission oscillations during the impulsive phase. The above similar oscillations suggest that the EUV oscillations during preflare phase are possibly associated with the radio oscillations during the flaring impulsive phase. The doom-like coronal magnetic field structure are analyzed and MUSER decimetric radio burst observations may play an important role in association with the initiation of the CME process.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMSH13A..07Y