Precise Masses for Wolf 1062 AB from Hubble Space Telescope Interferometric Astrometry and MCDonald Observatory Radial Velocities
McArthur, B. E.; Benedict, G. F.; Franz, O. G.; Bradley, A. J.; Hemenway, P. D.; Jefferys, W. H.; Nelan, E.; Shelus, P. J.; Story, D.; Whipple, A. L.; Duncombe, R. L.; Fredrick, L. W.; Wasserman, L. H.; Henry, T. J.; Takato, T.; Strateva, I. V.; Crawford, J. L.; Ianna, P. A.; McCarthy, D. W.; van Altena, W.
United States
Abstract
We present an analysis of astrometric data from Fine Guidance Sensor 3 (FGS 3), a white-light interferometer on HST, and of radial velocity data from two ground-based campaigns. We model the astrometric and radial velocity measurements simultaneously to obtain parallax, proper motion, and component masses for Wolf 1062 (Gl 748; M3.5 V). To derive the mass fraction, we relate FGS 3 fringe scanning observations of the science target to a reference frame provided by fringe tracking observations of a surrounding star field. We obtain an absolute parallax (πabs=98.0+/-0.4 mas) yielding MA=0.379+/-0.005 Msolar and MB=0.192+/-0.003 Msolar, high-quality component masses with errors of only 1.5%. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.