BE-URSAE-MAJORIS - PRECATACLYSMIC BINARY-SYSTEM AND PLANETARY NUCLEUS

This paper presents new spectrophotometric observations and a new anal ysis of the hot and cool components of the evolved binary system BE Ur sae Majoris, and we report the discovery of a planetary nebula around it. The primary star can be classified as a subdwarf O or borderline D AO white dwarf with T(eff) = 105,000 K +/- 11,000 K, log g = 6.5 +/- 0 .25, based on NLTE model atmosphere profile fits to the H and He II li nes. Observations of the secondary during eclipse indicate a spectral type of K5. Its estimated brightness during eclipse is consistent with a main-sequence star of K5 at the distance of 1.9 kpc derived from an alysis of the primary star. The nebula is roughly circular with a diam eter of 3'. This corresponds to a physical diameter of 1.5 pc at the e stimated distance.