Metallicity estimates for A-, F-, and G-type stars from the Edinburgh-CapeBlue Object Survey

The Edinburgh-Cape Blue Object Survey is an ongoing project to identify and analyse a large sample of hot stars selected initially on the basis of pho tographic colours (down to a magnitude limit B similar to 18.0) over the en tire high-Galactic-latitude southern sky, and then studied with broad-band UBV photometry and medium-resolution spectroscopy. Due to unavoidable error s in the initial candidate selection, stars that are likely metal-deficient dwarfs and giants of the halo and thick-disc populations are inadvertently included, yet are of interest in their own right. In this paper we discuss a total of 206 candidate metal-deficient dwarfs, subgiants, giants, and ho rizontal-branch stars with photoelectric colours redder than (B - V)(o) = 0 .3, and with available spectroscopy. Radial velocities, accurate to similar to 10-15 km s(-1), are presented for all of these stars. Spectroscopic met allicity estimates for these stars are obtained using a recently recalibrat ed relation between Ca II K-line strength and (B - V)(o) colour. The identi fication of metal-poor stars from this colour-selection technique is remark ably efficient, and competitive with previous survey methods. An additional sample of 186 EC stars with photoelectric colours in the range -0.4 less t han or equal to (B - V)(o) < 0.3, composed primarily of field horizontal-br anch stars and other, higher gravity, A- and B-type stars, is also analysed . Estimates of the physical parameters T-eff, log g, and [Fe/H] are obtaine d for cooler members of this subsample, and a number of candidate RR Lyrae variables are identified.