Narrow-band Type II Emissions Associated with CMEs of Large Angular Widths: A New Characteristics for Metric Type II bursts

Abstract

In this study, We correlated frequency bandwidth of 12 Type II bursts to the angular width of the associated CMEs and obtained an anticorrelation coefficient of ~ 60 % suggesting that the CMEs with large angular widths could produce narrow-band Type II emissions, in stark contrast to the recent report[1], that they produce broad-band Type II emissions. We further deduced the height of the Type II bursts (rType II ) at the onset time of the burst was < CME height (rCME), suggesting that the Type II emissions could be produced in the flank region of the shock rather than in the shock front