A WHITE-DWARF COMPANION TO THE B5-V STAR HR-2875 (Y-PUPPIS)

An extreme-ultraviolet source in the EUVE and ROSAT Wide Field Camera catalogs, also identified with a very soft ROSAT PSPC X-ray source, is coincident with the B5 V star HR 2875 (y Pup). We present an analysis of PSPC and EUVE spectra revealing the presence of a hot white dwarf companion to HR 2875, which then constitute the first confirmed B star plus white dwarf system. The B star shows variable Si II, He I, and H I line profiles in high-dispersion spectra, possibly related to its b inary nature, but our measurements limit the radial velocity semiampli tude of the B star to less than or equal to 2 km s(-1). We speculate t hat the white dwarf is most likely massive, and we propose some observ ational tests of the model.