Abstract

The Nobeyama Radioheliograph, a radio interferometer dedicated for solar observations, is designed to be suitable for observations of solar flares. However, its wide field of view and high dynamic range enable us to study prominence eruptions. In contrast to H alpha, 17 GHz images are not affected by Doppler shift due to the motion of prominences. We found evidence that temperature of prominences increases at their eruptions in two events on 1992 November 5 and on 1994 February 20. A prominence on the disk is observed as a dark filament at 17 GHz, because the temperature of a prominence is lower than that of the disk. At the two events analyzed, prominences apparently disappear, after they start to erupt. However, when the prominences pass plage regions, they ``hide'' the plages. This fact means that the prominence is still optically thick during eruptions but they are heated up to the temperature of the disk. Heating of prominence material is important to consider the relation between the eruption of cool matter seen in H alpha and that of hot matter seen in He-lines and white-light corona.