A study of the IC 5146 dark cloud complex

Abstract

The IC 5146 dark cloud complex has been studied in the infrared in order to identify and study associated young stellar objects. Most of the objects detected in the survey appear to be field stars, predominantly late-type giants. Three young objects were detected in the survey: the B0 star BD +46 deg 3474, the Ae star BD +46 deg 3471, and a previously unidentified object which appears to be a heavily obscured FU Orionis star. The properties of the last two objects are examined in detail, and an attempt is made to produce reasonable models for them. It is suggested that FU Orionis stars are binaries, and some consequences of this model are described. Photometry of the brighter stars in the IC 5146 cluster has been used to establish a distance to the cluster of 900 + or - 100 pc.