Stellar-Population Samples at the Galactic Poles. II. UBVRI Photometry of M Stars Near the South Pole
About 950 UB V and 8501?' observations have been obtained for 109 red stars near the South Galactic Pole. All except nine of the HD stars of types Ma, Mb, and Mc within 30 of the South Galactic Pole and all except eleven of the Ma stars within 20 are included. Of the Ma stars, 14 percent are found to be variable, with 11 percent showing erratic (EC) variations and 3 percent being quasi-periodic (P). A total of thirty-eight, or 72 percent, of the Mb stars are variable; four of these are named variables. The variables of class Mb are equally divided between nineteen EC and nineteen P types. All Mc and Md stars are variable. The 105 HD stars of type M observed yielded a total of sixty variables, of which forty-three are new. Four additional known variables, U, X, SY, and TT Scl, which are near the South Galactic Pole but not in the HD, were also observed. Proper motions have been collected, or derived, for most of the stars, and the luminosities obtained from the (M1, R -1)-relation yield relatively accurate space-motion components (U, V), with which population discrimination can be made. Mso the position in the (U - B, R - 1)-plane is discussed and used as a population indicator. The young disk stars reach a ceiling at about 400 pc from the plane, the old disk stars at about 900 pc, and the halo objects are distributed up to 1200 pc. The old disk variables have a space density of about four er 10 pc3 the halo variables, one per 10 pc3. O servations of early-t e stars, on the UBV system, indicate a uniform reddening of E(B - V) = +0.025 mag at the South lactic Pole.