Radio signatures of a fast coronal mass ejection development on November 6, 1997

Abstract

The Oporto radiospectrograph and the Nançay radioheliograph recorded a radio event on November 6, 1997, closely related in time with a flare on National Oceanic and Atmospheric Administration (NOAA) active region 8100. At the beginning of the event the radio sources are located on a rather small volume in the vicinity of the flare site. In a timescale of only a few minutes the radio emission sites spread over a large volume in the corona, covering a range of 100° in heliolatitude. During the period of the radio event the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) observed an extremely fast coronal mass ejection (CME), with a velocity around 2000 km s −1 . This CME presents the particularity of having a fast lateral expansion, giving it a shape reminiscent of a “coat hanger.” There is a very good association between the latitudinal extent and time development of the CME seen by LASCO and the radio sources recorded by the radio instruments.