A FLARE-ASSOCIATED FILAMENT ERUPTION OBSERVED IN SOFT X-RAYS BY YOHKOH ON 1992 MAY 7

Yohkoh soft X-ray image data prior to a filament activation and erupti on on 1992 May 7 reveal the presence of a bright, filamentary soft X-r ay structure apparently lying low under an arcade of soft X-ray loops from which the eruption later originated. This filamentary soft X-ray feature was coexistent and partially co-spatial along the line-of-sigh t direction with a dark He I 1083 nm filamentary structure (which was similar in appearance to an Her dark filament observed earlier). Prior to the start of the flare the apparently low-lying filamentary soft X -ray structure disappeared, but a bright linear feature was then seen just below several clearly visible overlying loops? consistent with th e filamentary soft X-ray feature having risen in altitude. At the same time the H alpha dark filament became elevated and overlapped well, a long the line-of-sight direction, with the elevated linear soft X-ray feature. Some of the overlying loops brightened in soft X-rays at the time the Her data show the Her filament in an elevated position and ri sing, (but before the Her dark filament disappearance). The overlying soft X-ray loops also showed an increase in temperature and emission a t the time of the filament activation. Eventually the elevated, filame ntary soft X-ray feature disappeared and several apparently cusped sha ped loops were then observed in the vicinity. Within several minutes o f this time the soft X-ray flare occurred. The series of Yohkoh soft X -ray images for this event together with supporting data from ground-b ased observatories strongly suggest that many features of the magnetic field changes associated with the eruption of the filament were seen in soft X-rays. Moreover the observations indicate that the filament a nd overlying arcade should be considered to be semi-independent struct ures that can interact with each other, rather than as parts of a larg e single structure, as is often assumed. We also find two types of cus ped loops in this event. The first type consists of several distinct n arrow cusped loops prior to the flare, while the second type consists of diffuse cusped loop structures which appear to lie above the bright est parts of the bright arcade during gradual phase of the flare. Evid ence is also presented which indicates that a nearby parasitic polarit y emerging flux region may have played a role in destabilizing the arc ade region, causing the filament activation, eruption and flare. The c hanges in the magnetic field extend beyond the flaring arcade to inclu de the creation of a transient coronal hole and a dark coronal channel near the arcade.