First VLA Observations of Nonthermal Metric Bursts Associated with Coronal Mass Ejections Detected by the [ITAL]Solar and Heliospheric Observatory[/ITAL

Abstract

We present the first observations of nonthermal decimetric burst emission of the Sun using the new 400 cm (74 MHz) system at the VLA. Our VLA observations were carried out in collaboration with the Large Angle Spectroscopic Coronagraph (LASCO) and the Extreme-Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory spacecraft. Full-disk observations at 400 and 91 cm were used to study the spatial and temporal variations of nonthermal radio bursts during coronal mass ejections (CMEs) detected by LASCO as well as transient extreme-ultraviolet brightenings detected by the EIT. VLA snapshot maps at 400 cm revealed impulsive burst emission in the low corona that began near the estimated start time of the CME activity; that beginning also coincided with a C1.1 GOES X-ray burst and an EIT flarelike brightening. The nonthermal metric bursts then continued sporadically during the next several hours, which included the ejection of spatially separated CME components. The 400 cm bursts are contained within curved, or archlike, sources at a fixed radial distance but with a varying position between two active regions detected by the EIT near the limb, suggesting that they were emitted within large-scale magnetic loops. Our 91 cm observations also show the onset of a long-lasting type I noise storm following the initiation of CME activity, again suggesting an intimate relationship between the production of nonthermal particles and large-scale evolving plasma-magnetic field structures in the corona.