HALO BLUE HORIZONTAL BRANCH STARS - SPECTROSCOPY IN 2 FIELDS

We present results of spectroscopic observations at 2-angstrom resolution of 44 stars in two fields. 39 are identified as blue horizontal branch (BHB) stars, RR Lyrae or main-sequence A stars. The candidates were selected by colour from digitized UK Schmidt direct plates and by the presence of a strong Balmer discontinuity in their objective prism spectra. Velocities and distances are measured for each of the BHB candidates. At moderate spectral dispersion the distinction between main-sequence A stars and horizontal branch stars cannot be made on the basis of hydrogen linewidths alone. Four stars at a distance of 30 kpc in one field (F826) are found to have a velocity dispersion of less than 12 km s-1, and a systematic velocity of 70 km s-1 with respect to the Galactic rest frame. These stars are not bound to each other but may be the stellar remnants of a recently disrupted halo cluster.