  We present the results of an HST snapshot program to search for very-low-mass
stellar companions to nearby M subdwarfs. None of our nine targetted metal-poor
primaries have companions more massive than the hydrogen burning limit,
implying that the halo binary fraction is equal to or less than the Galactic
disk binary fraction below 0.3 M_sun. In addition, the more distant tertiary
VB12, an sdM3.0 companion to an F subdwarf double, is also unresolved. We show
that the relation between WFPC2 F555W and F850LP photometry and ground V,I
photometry is consistent with theoretical expectations. We also report that two
recently observed Hyades M dwarfs appear single.

Astrophysics