Simultaneous HST/ASCA Observations of LMC X-4: X-ray Ionization Effects on a Stellar Wind

We present first results from simultaneous ultraviolet (HST/GHRS) and X-ray (ASCA) observations of the 13.5s pulsar LMC X-4 taken in 1996 May. The ASCA observations covered 1.12 binary orbits (1.58 days) and the HST observations were centered on this for roughly 0.4 orbital phase coverage (0.56 days). The GHRS data are the highest resolution (both temporal and spectral) ultraviolet spectra ever taken of LMC X-4. With generally-accepted parameters Visiting Professor, Department of Astronomy, University of Maryland, College Park, MD 20742 Center for Space Science, Shanghai Jaio Tong University, Shanghai, 200023, People’s Republic of China