A DETERMINATION OF THE DISTANCE TO THE HIGH-VELOCITY CLOUD COMPLEX-M

The high-velocity cloud complex M has been detected in absorption towa rd the halo star BD + 38-degrees-2182 (z = 4.4 kpc) with the Internati onal Ultraviolet Explorer (IUE) echelle spectrograph. Absorption is se en out to - 120 km s-1 in the saturated resonance lines of C II, Si II , and 0 I. Data on highly ionized species of C IV and Si IV are too no isy to determine the presence or absence of absorption from highly ion ized gas at the velocities of complex M. The BD + 38-degrees-2182 data are compared to similar data for HD 93521, which lies 27 arcmin away, but at a z-distance of only 1.5 kpc. The absorption line detection to ward BD +38-degrees-2182, along with the lack of observed absorption a t v < - 85 km s-1 toward HD 93521 places the distance to complex M at 1.5 < z < 4.4 kpc. Complex M has a mass between 10(4) and 10(5) M., an d the lower limits on the column densities of C, 0, and Si are between 1.0 and 1.4 dex below solar metallicity.