Nonthermal Radio Signatures of Coronal Disturbances with and without Coronal Mass Ejections

Abstract

This study presents data on two events from the Extreme-UV Imaging Telescope (EIT) and the Large Angle and Spectroscopic Coronagraph instruments (C1, C2, and C3), Geostationary Operational Environmental Satellite (GOES) soft X-ray data, and 40-800 MHz radio spectra of the Astrophysical Institute Potsdam. At first glance, the two events appear similar. However, one event decays after a flare-related ejection of cold and hot matter into the lower corona causing only brightness changes in EIT and C1, while the other event marks the onset of a coronal mass ejection (CME) that propagates with a leading-edge speed of ~530 km s^-1 between 2 and 30 R_solar. The radio data reveal two differences between the CME and non-CME events: (1) a characteristic faint type III burst group in the time interval with the first clearly CME-related structural change in the coronagraph images and (2) a continuum emission with a frequency drift during the passage of the CME matter through the C1 field of view. Furthermore, we show that the radio spectral data can provide essential information on the timing of the early stages of CME formation and the initial mass motions associated with the ejection.