SIMULTANEOUS OBSERVATIONS OF A PROMINENCE ERUPTION FOLLOWED BY A CORONAL ARCADE FORMATION IN RADIO, SOFT X-RAYS, AND H-ALPHA

A prominence eruption followed by a coronal brightening was simultaneo usly observed in radio (17 GHz), soft X-rays, and Halpha on 1992 July 30-31. The observations were performed by newly developed high-perform ance instruments: the Nobeyama Radioheliograph, the SXT on the Yohkoh satellite, the Flare Monitoring Telescope of the Hida Observatory, and some other Halpha telescopes. This event gives us a much more detaile d picture of this type of phenomena than previously observed. The erup ting prominence, which occurred in a quiet region and was observed in Halpha and radio, ascended with a velocity of about 100 km s-1. The ge neral structure of the erupting prominence seen at 17 GHz is very simi lar to that at Halpha. While the prominence expanded rapidly, the tota l radio flux of the erupting prominence did not change very much. Sinc e a prominence consists of fine threads, this fact means that each thr ead did not expand while the prominence expanded. Consequently, the su rface filling factor of the prominence must have decreased during the eruption. The high-resolution pictures of a clear coronal arcade struc ture were taken in soft X-rays and radio after the prominence eruption ; the physical parameters of the arcade were derived from these pictur es. The mean temperature was 3.5 x 10(6) K in the early phase, and dec reased to 2.6 x 10(6) K within seven hours. The total emission measure reached a maximum value of 1.6 x 10(48) CM-3 after three hours from t he beginning of the arcade brightening, when the electron density at t he ridge of the arcade is estimated as 2.4 x 10(9) CM-3. The temporal and spatial relationship between the erupting prominence and the coron al arcade is shown. It gives an observational restriction to the magne tic field configuration of the models of such events.