The broken lane of a type II radio burst caused by collision of a coronal shock with a flare current sheet

Abstract

We investigated a peculiar metric type II solar radio burst with a broken lane structure that was observed on November 13, 2012. In addition to the radio data, we also studied the data in other wavelengths. The bursts were associated with two coronal mass ejections (CMEs) and two flares that originated from Active Region AR 11613. A long current sheet developed in the first CME, and the second CME collided with the current sheet first and then merged with the first CME. Combined information revealed by the multi-wavelength data indicated that a coronal shock was accountable for the type II radio burst and that the collision of this shock with the current sheet resulted in the broken lane of the type II radio burst. The type II burst lane re-formed after the shock passed through the current sheet. Furthermore, we estimated the thickness of the current sheet from a gap in the lane of the type II burst, and found that the result is consistent with previous ones obtained for various events observed in different wavelengths by different instruments. In addition, the regular type II burst associated with the first CME/flare was also studied, and the magnetic field in each source region of the two type II bursts was deduced in different ways.