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G. F. Benedict, B. E. McArthur (McDonald Observatory), Are There Planets or Not? Team
Using FGS 1r, a white-light interferometer on HST, we carried out narrow-field relative astrometry of \epsilon Eri, a star possibly hosting a planetary mass companion (Hatzes et al. 2000, ApJL,544, 145). Following the approach used to establish the mass of the extrasolar planet Gl 876 b (Benedict et al. 2002, ApJL, 581, 115), we combine three years of HST astrometric observations with ground-based primary star high-precision radial velocities from McDonald, Lick, and CFHT Observatories, spanning more than one companion period. Unlike our previous approach, this study also includes ground-based, lower per-observation precision astrometry. Nearly fifteen years of Allegheny Observatory MAP data considerably extend our time span. At a minimum, these data improve the precision of our final proper motion, a signature, along with parallax, that must be removed to yield orbital acceleration. We present the major result of our final analysis, the mass of \epsilon Eri b.
The 'Are These Planets or Not?' Team for this particular object consists of the authors and co-I's; A. Hatzes, W. Cochran, G. Marcy, P. Butler, G. Walker, and B. Campbell. This research is supported by grant GO-9969 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.