OPTICAL AND 21-CM OBSERVATIONS OF HIGH-VELOCITY GAS TOWARDS SUBDWARFSIN THE HALO AND EARLY-TYPE STARS IN THE DISK

We present a study of high-velocity gas in the direction of 13 halo su b-dwarfs located at \z\ similar or equal to 0.5 - 2 kpc and of 8 early -type stars in the Galactic disk at d similar or equal to 1 - 4 kpc. F or each line of sight of our sample we collected Ca II and Na I absorp tion spectra with the 2.5-m Isaac Newton Telescope at La Palma (Spain) and H I 21-cm emission profiles with the 100-m radiotelescope at Effe lsberg (Germany). The faint sub-dwarfs (m(V) similar or equal to 11-14 ) are observed for the first time at relatively high spectral resoluti on (similar or equal to 25 - 30 km s(-1)) in the optical. By comparing the optical absorptions (or upper limits) with the 21-cm emissions, w e constrain the distances to the concentrations of neutral gas at high velocity named Complex C, Complex H, and for high velocity gas locate d between the Cohen Stream and the Magellanic Stream, We find new evid ence for gas at intermediate velocity in the halo and in the disk of o ur Galaxy.