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arXiv · 1203.1511

A broken solar type II radio burst induced by a coronal shock propagating across the streamer boundary

Xiang-Liang Kong·Yao Chen·Gang Li·Shi-Wei Feng·Hong-Qiang Song·Fan Guo·Fang-Ran Jiao
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Abstract

We discuss an intriguing type II radio burst that occurred on 2011 March 27. The dynamic spectrum was featured by a sudden break at about 43 MHz on the well-observed harmonic branch. Before the break, the spectrum drifted gradually with a mean rate of about -0.05 MHz/s. Following the break, the spectrum jumped to lower frequencies. The post-break emission lasted for about three minutes. It consisted of an overall slow drift which appeared to have a few fast drift sub-bands. Simultaneous observations from the Solar TErrestrial RElations Observatory (STEREO) and the Solar Dynamics Observatory (SDO) were also available and are examined for this event. We suggest that the slow-drift period before the break was generated inside a streamer by a coronal eruption driven shock, and the spectral break as well as the relatively wide spectrum after the break is a consequence of the shock crossing the streamer boundary where density drops abruptly. It is suggested that this type of radio bursts can be taken as a unique diagnostic tool for inferring the coronal density structure, as well as the radio emitting source region.

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Xiang-Liang Kong, Yao Chen, Gang Li, Shi-Wei Feng, Hong-Qiang Song, Fan Guo, Fang-Ran Jiao. 2012-03-07. A broken solar type II radio burst induced by a coronal shock propagating across the streamer boundary. https://doi.org/10.1088/0004-637x%2F750%2F2%2F158

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