Precise Masses for Wolf 1062 AB from Hubble Space Telescope Interferometric Astrometry and McDonald Observatory Radial Velocities

摘要

We present an analysis of astrometric data from FGS 3, a white-lightinterferometer on {it HST}, and of radial velocity data from two ground-basedcampaigns. We model the astrometric and radial velocity measurementssimultaneously to obtain parallax, proper motion and component masses for Wolf1062 = Gl 748 AB (M3.5V). To derive the mass fraction, we relate FGS 3 fringescanning observations of the science target to a reference frame provided byfringe tracking observations of a surrounding star field. We obtain an absoluteparallax $pi_{abs} = 98.0 pm 0.4$ milliseconds of arc, yielding ${cal M}_A =0.379 pm 0.005{cal M}_{sun}$ and ${cal M}_B= 0.192 pm 0.003 {calM}_{sun}$, high quality component masses with errors of only 1.5%.