CH+ IN THE INTERSTELLAR-MEDIUM

This paper describes observations of interstellar CH+ along the lines of sight to O and B stars with E(B - V)s up to +1.13. Along some lines of sight with strong detections of CH+, we find distinct radial veloc ity shifts between the CH+ lines and other neutral species, such as Ca I and CH. The shifts are small but are predicted by shock models of C H+ formation in which the shock is inclined with respect to the observ er. We have also found no column densities exceeding approximately 10( 13.8) cm-2. When these data are examined along with other CH+ data col lected from the literature, the previously seen tendency of CH+ column density to increase with E(B - V) does not continue beyond reddenings of about +0.6. These findings offer support to the shock model of CH formation for at least some lines of sight.