Interstellar reddeningh law towards the nucleus of H Per.

Abstract

The extinction curves in the direction of four early-B main-sequence stars located in the nucleus of h Per (BD + 56 deg 501, BD + 56 deg 510, BD + 56 deg 516 and BD + 56 deg 517) and compared to one another and to the extinction curves derived from eight stars located in the same general area but lying at different distances. Data from UBV photometry and low-dispersion UV (IUE) spectroscopy were used to derive the curves. The interstellar reddening law along the line of sight of the four h Per stars is constant. The extinction curves match the curves derived from stars located in the region of the Perseus arm surrounding the cluster. This result suggests that the interstellar medium in the h Per direction has properties similar to those of the general h and Chi Per direction. There is a rather smooth decrease in the extinction per unit distance with increasing height from the galactic plane, which is consistent with the lower density of the interstellar medium away from the galactic plane. There is no indication of a variation of the ratio bump strength to far-UV extinction with distance.