Howard E.Bond, Space Telescope Science Institute, 3700 San Martin
Drive, Baltimore, MD 21218, USA
I will describe an ongoing program, carried out by myself and D. Pollacco, in which we are monitoring Sakurai's Object with the Hubble Space Telescope. The original aim of the program was to follow the evolution of the central star back to high temperatures, including a regular series of UV spectroscopic observations with STIS to witness the re-establishment of a fast stellar wind. This evolution back to high temperatures has, however, not yet occurred, so the spectroscopic observations await activation as a `target-of-opportunity' program. At the moment, we are left with a series of WFPC2 images that we have obtained regularly since 1996 at the rate of 1-3 frames per year. These set some limits on the presence of light echoes, and will provide baseline images for the eventual appearance of resolved structures in material ejected during the current outburst.
I will also discuss HST FOC images of the related object V605 Aql, which reveal a resolved nebula ejected during the outburst early in the 20th century. I will conclude by mentioning briefly a few other planetary nebulae with late-type nuclei showing no evidence (in IUE UV spectra) for hot companions; it is thus possible that the late-type objects are the central stars, undergoing `born-again' episodes similar to those of Sakurai's Object, V605 Aql, and FG Sge.