A multiwavelength study of an M-class flare and the origin of an associated eruption from NOAA AR 11045

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• 作者：B.N. Dwivedi^a ; ^{bholadwivedi@gmail.com} ; Abhishek K. Srivastava^b ; Mukul Kumar^a ; Pankaj Kumar^c
• 关键词：Corona ; Solar flares ; Reconnection ; CME
• 刊名：New Astronomy
• 出版年：2012
• 期刊代码：39_13841076
• 类别：ph
• 出版时间：July, 2012
• 卷：17
• 期：5
• 页码：542-551
• 文件大小：4232 K

摘要

In this paper, we study multiwavelength observations of an M6.4 flare in Active Region NOAA 11045 on 7 February 2010. The space- and ground-based observations from STEREO, SoHO/MDI, EIT, and Nobeyama Radioheliograph were used for the study. This active region rapidly appeared at the north-eastern limb with an unusual emergence of a magnetic field. We find a unique observational signature of the magnetic field configuration at the flare site. Our observations show a change from dipolar to quadrapolar topology. This change in the magnetic field configuration results in its complexity and a build-up of the flare energy. We did not find any signature of magnetic flux cancellation during this process. We interpret the change in the magnetic field configuration as a consequence of the flux emergence and photospheric flows that have opposite vortices around the pair of opposite polarity spots. The negative-polarity spot rotating counterclockwise breaks the positive-polarity spot into two parts. The STEREO-A 195 脜 and STEREO-B 171 脜 coronal images during the flare reveal that a twisted flux tube expands and erupts resulting in a coronal mass ejection (CME). The formation of co-spatial bipolar radio contours at the same location also reveals the ongoing reconnection process above the flare site and thus the acceleration of non-thermal particles. The reconnection may also be responsible for the detachment of a ring-shaped twisted flux tube that further causes a CME eruption with a maximum speed of 446 km/s in the outer corona.