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 ac- tivation and eruption on 1992 May 7 reveal the presence of a bright, filamentary soft X-ray 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 coex- istent and partially co-spatial along the line-of-sight direction with a dark He I 1083 nm filamentary structure (which was similar in appearance to an H dark filament observed earlier). Prior to the start of the flare the apparently low-lying filamen- tary soft X-ray structure disappeared, but a bright linear feature was then seen just below several clearly visible overlying loops, consistent with the filamentary soft X-ray feature having risen in altitude. At the same time the H dark filament became el- evated and overlapped well, along the line-of-sight direction, with the elevated linear soft X-ray feature. Some of the overly- ing loops brightened in soft X-rays at the time the H data show the H filament in an elevated position and rising, (but before the H dark filament disappearance). The overlying soft X-ray loops also showed an increase in temperature and emission at the time of the filament activation. Eventually the elevated, fil- amentary soft X-ray feature disappeared and several apparently cusped shaped loops were then observed in the vicinity. Within several minutes of 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-based observatories strongly sug- gest that many features of the magnetic field changes associated with the eruption of the filament were seen in soft X-rays. More- over the observations indicate that the filament and overlying arcade should be considered to be semi-independent structures that can interact with each other, rather than as parts of a large single structure, as is often assumed. We also find two types of cusped loops in this event. The first type consists of several