A stable filament cavity with a hot core

We present observations of a long-lived solar filament cavity with soft X-r ay sources along its axis. This structure appeared above the southern polar crown polarity-inversion line for approximately three rotations during 199 7 June-August, centered at a west-limb passage on approximately July 3. At the limb, the Yohkoh soft Xray data showed a blight region situated above a nd around the projected filament location but near the axis of the cavity. We describe measurements of the geometry of the cavity, which we interpret as a flux rope that is partially embedded in the photosphere, and use the Y ohkoh data to describe the physical parameters of the structure. We find th at the core consists of an unresolved mass of filamentary substructures, wi th a volume filling factor significantly less than unity for the soft X-ray telescope (SXT) resolution. The core has a higher temperature than the cav ity surrounding it, ruling out explanations in terms of a transition region supported by thermal conduction. Transient activity occurred in the polar crown region, but no detectable destabilization or eruption of the cavity s tructure resulted from it. We suggest that the bright structure at the core of the cavity corresponds to higher altitude coronal segments of the field lines that support the filament material.