A Search for Unresolved Double Degenerates Using IUE Archives.pdf

14th European Workshop on White Dwarfs ASP Conference Series, Vol. 999, 2005 D. Koester, S. Moehler A Search for Unresolved Double Degenerates Using IUE Archives C.-P. Lajoie and P. Bergeron D´epartement de Physique, Universit´e de Montr´eal, C.P. 6128, Succ. 5 Centre-Ville, Montr´eal, Qu´ebec, Canada, H3C 3J7 0 0 2 Abstract. We present preliminary results of a study aimed at detecting r double white dwarf systems using a method based on a comparison of optical a and UV spectra for 141 DA stars drawn from the IUE archives. In particular, M we are looking for dicrepancies between optical and UV temperatures. Even though known unresolved degenerate binaries stand out in this comparison, most 8 temperature differences can probably be attributed to the presence of reddening, or the presence of heavy elements. We are in the process of securing additional 1 optical spectroscopic observations to increase the number of stars in our analysis. v 1 9 1 3 1. Introduction 0 5 Stellar evolution theory predicts that there should exist a population of white 0 / dwarfs in binary systems with combined masses exceeding the Chandrasekhar h limit. If such systems have a short enough orbital period, merger within a Hubble p - time will make them possible candidates for type Ia supernovae progenitors. o The problem is that very few double degenerates (DDs) are actually known to r t