We report spectroscopic observations of the red giant star HR 5692, previously known to be a binary system both from other spectroscopic work and from deviations in the astrometric motion detected by the Hipparcos satellite. Earlier International Ultraviolet Explorer (IUE) observations had shown the presence of a hot white dwarf companion to the giant primary. We have combined our radial velocity observations with other existing measurements and with the Hipparcos intermediate astrometric data to determine a complete astrometric-spectroscopic orbital solution, providing the inclination angle for the first time. We also determine an improved parallax for the system of 10.12 ± 0.67 mas. We derive the physical properties of the primary, and with an estimate of its mass from stellar evolution models (1.84 ± 0.40 M sun), we infer the mass of the white dwarf companion to be M WD = 0.59 ± 0.12 M sun. An analysis of an IUE white dwarf spectrum, using our parallax, yields T eff = 30, 400 ± 780 K, log g = 8.25 ± 0.15, and a mass M WD = 0.79 ± 0.09 M sun, in marginal agreement with the dynamical mass.
