High velocity interstellar C IV and SI IV toward two stars in the I Per OB association.

Abstract

Blue-shifted interstellar C IV, Si IV and Al III lines have been detected in the IUE spectra of the B2Ia stars HD 14818 and HD 14143; which are members of the I Per OB association. The radial velocities and column densities of these high ion state lines are similar toward the two stars. These observations, together with previous optical and radio observations, suggest that a shell of gas expanding away from the OB association at about 25 km/sec is being observed. The most likely explanation is that the expanding shell has been produced by a very large supernova event or a number of normal Type II supernovae, with stellar winds from the hot supergiant stars in the association providing a secondary energy source. Theoretical considerations and observations of others suggest that this phenomenon may be quite common.