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Session 79 - White Dwarf Stars.
Display session, Wednesday, January 15
We present far ultraviolet and optical spectroscopy of the Extreme Ultraviolet Explorer\/ (EUVE\/) survey source EUVE J0702+129 showing a composite K0 star plus DA white dwarf spectrum. International Ultraviolet Explorer spectra show continuum emission from a hot white dwarf (T_eff =30-40,000 K) and a rising contribution from the K0 star at \lambda \geq 2500 ÅHigh resolution optical spectroscopy reveals a moderate level of activity with Ca II H amp; K emission; application of the Wilson-Bappu relation indicates that the secondary star is slightly above the main-sequence (K0 IV--V). Both objects are found at a distance of \sim100 pc and probably constitute a physical pair. The EUV emission is probably dominated by the white dwarf, but the late-type star possibly contributes at higher energy. Interesting parallels are drawn with other DA+K0 pairs with moderately active secondaries such as HD 18131 and HR 1608. The present discovery as well as other recent ones demonstrate the existence of a large population of white dwarfs hidden by evolved companions (III--IV). This work is supported by NASA grant NAG-2405 and contract NAS5-29298.
Program listing for Wednesday