Previous abstract Next abstract
We present the analysis of 14 orbital phase-resolved IUE (large and small aperture), SWP spectra, sampling the quiescent interval of the prototype dwarf nova U Geminorum following two individual outbursts, the outburst of 1992, 29 August-14 September and the outburst of 1993, 19 March-5 April. During quiescence the photospheric radiation of the exposed white dwarf dominates the ultraviolet (Kiplinger, Sion and Szkody 1991,ApJ,366,569; Long et al.1993,ApJ,405,327). The variations in absorption line strengths and continuum flux levels are analyzed as a function of both orbital phase and time of observation since the return to optical quiescence, by fitting the IUE spectra with a grid of high gravity, LTE, model atmospheres with solar composition (and fractional composition thereof)constructed with I. Hubeny's TLUSTY code. The absorption line strengths and flux levels are compared with Hubble FOS and GHRS spectra obtained early and late in quiescence following the outburst of 1992, 29 August. Spectroscopic changes of the white dwarf associated with the accretion process are compared with theoretical simulations of disk accretion and implications are discussed.
This research was supported by NASA grants NAGW5184 and GO-3836.01-91A to Villanova University.
Thursday program listing