Population studies. I - The Bidelman-MacConnell 'weak-metal' stars

BVRI and DDO photometry together with kinematic data are presented for the spectroscopically chosen sample of Bidelman-MacConnell (BM) "weak-metal" stars. Analysis yields chemical abundances and space motions, which are compared with those of the kinematically selected sample of Eggen, Lynden-Bell, and Sandage (ELS). The BM sample appears to contain a significant proportion of low-abundance, low-eccentricity objects, in contrast to the results of ELS (≡ 20% of BM objects with [Fe/H] ≤ -1 have e ≤ 0.4). The velocity dispersion of such stars perpendicular to the galactic plane is 60±9 km s⁻¹. Finally, for stars with [Fe/H] ≤ -1.2 the velocity ellipsoid is described by σu = 125±11, σv = 96±9, σw = 88±7 km s⁻¹.