Infrared Studies of Two Dark Clouds

Citation

Elias, Jonathan H. (1978) Infrared Studies of Two Dark Clouds. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/78t4-q193. https://resolver.caltech.edu/CaltechETD:etd-09022008-145925

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The IC5146 dark cloud complex has been surveyed 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 BO star BD+4[…]3474, the Ae star BD+46[…]3471, and a previously unidentified object which appears to be a heavily obscured FU Ori 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 Ori stars are binaries, and some consequences of this model are described. Photometry of the brighter stars in the IC5146 cluster has been used to establish a distance to the cluster of 900 ± 100 pc. A near-infrared survey has also been conducted of nearly 18 square degrees of the Ophiuchus dark cloud complex. Additional observations have been made of selected objects found in this survey and of the brighter objects found by Grasdalen et al. and by Vrba et al. in this region, in order to identify and study the young stars associated with the cloud. These observations show that very recent star formation has been largely restricted to a small region no more than a few parsecs in extent at the center of the dark cloud complex. Most of the young stars do not appear to be main sequence stars. At least three of these objects appear to be surrounded by infrared reflection nebulae. Many of the objects studied are background K and M giants which can be used to determine the near-infrared extinction due to the dark cloud.

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