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Microwave and hard X‐ray sources in two X‐class limb flares

 

作者: Hiroshi Nakajima,   Thomas R. Metcalf,  

 

期刊: AIP Conference Proceedings  (AIP Available online 1996)
卷期: Volume 374, issue 1  

页码: 393-401

 

ISSN:0094-243X

 

年代: 1996

 

DOI:10.1063/1.50973

 

出版商: AIP

 

数据来源: AIP

 

摘要:

We have analyzed two intense, extended microwave and hard X‐ray flares which occurred slightly behind the west limb and were accompanied by X‐class, long‐duration events (LDEs) in soft X‐rays. We have found that: (1) Both events have typical soft X‐ray properties of LDEs. (2) A major hard X‐ray source at 23–33 keV and 33–53 keV is located in the high‐temperature region, considerably higher than the corresponding soft X‐ray loop, while a 17 GHz microwave source, where electrons at energy ≥ several hundreds keV mainly contribute to the 17 GHz emission, nearly coincides with the soft X‐ray loop in extent. (3) The electron spectrum, which is derived from the microwave spectrum, is significantly harder than the electron spectrum at energy ≤100 keV, which is derived from the hard X‐ray data. (4) The time profile of total intensity at 17 GHz is delayed by about 25 s with respect to that of the hard X‐rays for one of the events. The above results show evidence that lower‐energy (≤100 keV) electrons with a softer spectrum are accelerated at the top of the cusp, and that higher‐energy (≫100 keV) electrons are accelerated at the top of the soft X‐ray loop and trapped. Probably, the lower‐energy electrons accelerated in the cusp are transferred by a reconnection outflow into the second acceleration region at the top of the soft X‐ray loop, and further accelerated to higher energy. ©1996 American Institute of Physics.

 

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