Observations and orbital analysis of the giant white dwarf binary system HR 5692.
STEFANIK R.P., TORRES G., LATHAM D.W., LANDSMAN W., CRAIG N. and MURRETT J.
Abstract (from CDS):
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☉), we infer the mass of the white dwarf companion to be MWD= 0.59±0.12 M☉. An analysis of an IUE white dwarf spectrum, using our parallax, yields Teff = 30, 400±780 K, log g = 8.25±0.15, and a mass MWD= 0.79±0.09 M ☉, in marginal agreement with the dynamical mass.
binaries: general - methods: data analysis - stars: individual: HR 5692 - techniques: spectroscopic - white dwarfs