New Results from the Spectral Observations of Solar Coronal Type II Radio Bursts

Abstract

We carried out a statistical study of twenty-six type II radio bursts from the Sun observed with the Gauribidanur Low-frequency Solar Spectrograph in the frequency range 85–35 MHz during the period 2009–2019. Our results indicate that the average instantaneous bandwidth of the type II bursts in the above frequency range correlates with the angular width of the associated coronal mass ejections (CMEs). The correlation coefficient is ≈71%. This independently indicates that the coronal type II bursts reported in this work are mostly due to shocks driven by the CMEs. Moreover, it also suggests that the instantaneous bandwidth of the bursts could be due to electron acceleration (leading to type II bursts) occurring simultaneously at multiple locations of differing electron densities (i.e., plasma frequencies) along the shock surrounding the CME.