A Study of the Cepheus IV Association

Abstract

Membership in the Cepheus W association has been established for approximately forty 0 and B stars by means of spectral classification and photometry. Among these stars are three known Be stars, an eclipsing binary, and several stars in small reflection nebulosities. A new flare star and a new Be star may also be members. Surface distribution and photometry of a number of faint, variable Ha-emission stars in the region indicates that they are probably stars of T Tauri type associated with the dark cloud which obscures the most luminous members. The correlation between luminosity and reddening is confirmed; the 0 and early B stars were found only within the cloud, whereas the later B-type stars are found only outside the cloud due to the incompleteness of their detection. The surface distribution of field stars indicates a well-defined border to the cloud, and the ratio of total to selective absorption in the cloud is normal. The distance of the association is 845 pc, and its age is probably less than 2 X t(W years.