Shock-heated gas in the I Per OB association.

Abstract

In response to a suggestion by Phillips & Gondhalekar (1981) that hotgas is receding from the I Per OB association with a velocity of ≡30 km s^-1, the authors have examined the IUE high-dispersion spectra of stars in the association for blueshifted lines of interstellar C IV, Si IV and Al III. As a result, the high-velocity ions are now known to be present in front of at least five stars. The analysis of the radial velocities of the ions and of the column density ratio N(C IV)/N(Si IV) in the different sight-lines leads to a conclusion similar to that of Phillips & Gondhalekar, namely that the motion of the highly ionized gas is due to a supernova. The authors believe that the expansion of the H I shell in front of I Per is unrelated and that it is probably due to a recombining H II region within which the supernova event has occurred.