HUBBLE-SPACE-TELESCOPE OBSERVATIONS OF THE VERY-LOW MASS COMPANION TOGLIESE 105A

Hubble Space Telescope images of the astrometric binary G1 105A confir m the previous ground-based detection of a faint, very red companion ( G1 105C) located 3''.39 from G1 105A at P. A. 290 degrees. The instrum ental magnitudes of G1 105C are V-555 = 16.86 and I-814 = 13.54. The o bserved position of G1 105C differs significantly from the positions e xpected from current astrometric solutions. No other companions bright er than I-814 = 20.3 are seen between 1'' and 13''.5 from G1 105A. Usi ng the M dwarf model atmospheres of Allard and Hauschildt, we obtain f or G1 105C a standard color of V - I = 4.6, which suggests a spectral type of M7 V.