White Dwarfs in the Calan‐ESO Survey

Abstract

A sample of 33 white dwarfs (31 of them previously unknown) was recently discovered as a result of a proper-motion survey using red plates, which covered 350 deg2 in the sky. In this paper we present spectroscopic and photometric observations for all objects. The sample contains 15 non-DA white dwarfs (including several DQ and DZ stars) and 17 DA white dwarfs (including one DAZ star). One other object (CE 315) is an interacting double-degenerate and has been analyzed elsewhere. Atmospheric compositions, effective temperatures, and cooling ages have been estimated using model atmosphere fits to the observed fluxes. One white dwarf, CE 51, with a hydrogen-rich atmosphere, has a preliminary temperature estimate of only Teff = 2730 K, the coolest white dwarf identified so far in the literature. Atmospheric parameters for some DA stars in the sample have also been derived from fits to the high Balmer line profiles. From the present sample, a lower limit to the density of white dwarfs in the solar neighborhood, ρ = 5.6 × 10-3 pc-3, has been derived.