The very low mass component of the Gliese 105 system.
GOLIMOWSKI D.A., HENRY T.J., KRIST J.E., SCHROEDER D.J., MARCY G.W., FISCHER D.A. and BUTLER R.P.
Abstract (from CDS):
Multiple-epoch, multicolor images of the astrometric binary Gliese 105A and its very low mass companion Gliese 105C have been obtained using the Hubble Space Telescope's Wide Field Planetary Camera 2 (WFPC2) and near-infrared camera and multiobject spectrometer (NICMOS). The optical and near-infrared colors of Gl 105C strongly suggest a spectral type of M7 V for that star. Relative astrometric measurements spanning 3 yr reveal the first evidence of Gl 105C's orbital motion. Previous long-term astrometric studies at Sproul and McCormick Observatories have shown that the period of Gl 105A's perturbation is ∼60 yr. To satisfy both the observed orbital motion and Gl 105A's astrometric period, Gl 105C's orbit must have an eccentricity of ∼0.75 and a semimajor axis of ∼15 AU. Measurements of Gl 105A's radial velocity over 12 yr show a linear trend with a slope of 11.3 m.s–1.yr–1, which is consistent with these orbital constraints and a nearly face-on orbit. As no other faint companions to Gl 105A have been detected, we conclude that Gl 105C is probably the source of the 60 yr astrometric perturbation.
Stars: Binaries: Close - Stars: Individual: Alphanumeric: Gl 105AC - Stars: Low-Mass, Brown Dwarfs