Observations of an emission nebula associated with the carbon star UVAur.

Abstract

Optical and UV spectra from the stellar object UV Aur B were analyzed with model atmospheres and in terms of the UV absorption feature. The Coudespectrograph data were obtained with the ESO 1.5 m telescope. Three tracings of the B star spectrum indicated that the Balmer emission lines form in a nebula located between the two stars or mainly from a carbon star. The effective temperature and interstellar reddening of the B star were calculated to be 14,000 K and within 0.02 of 0.21, respectively. The B star rotational velocity was determined to be within 20 km/sec of 170 km/sec. A low value of the Lyman alpha flux indicated that the B star companion of UV Aur was not the ionizing source for the nebula, and the presence of a third star is suggested in the form of hot white dwarf with a temperature of at least 60,000 K.