The value of R in Monoceros

Abstract

Recent photometric and spectroscopic observations are used in conjunction with other data for early-type stars in northern Monoceros in order to investigate the local value of R (the ratio of total to selective extinction). From a variable-extinction analysis, it is concluded that a ratio of approximately 3.2 is appropriate for the general interstellar extinction in this region and that there is no evidence here for the existence of local anomalies. The two major associations Mon OB 1 and Mon OB 2 are clearly delineated and are found to exhibit properties typical of such young stellar groups. Derived properties for a few interesting stars are presented.