Star Formation in Sagittarius: The Lynds 291 Cloud

The Lynds 291 cloud in Sagittarius is a giant molecular cloud with ap- proximate dimensions 20 pc × 80 pc located at a distance of approximately 1700 pc. The northern part of the cloud is dominated by the HII region IC 1284 and the two reflection nebulae NGC 6589 and NGC 6595. The southwestern edge of the cloud con- sists of a high extinction ridge with numerous dense cores that are being compressed by an expanding HI bubble energized by OB stars and possibly several past supernova explosions. Star formation is taking place all along the ridge. A particularly well stud- ied source is IRAS 18162-2048, which drives the very luminous Herbig-Haro objects HH 80/81, a highly collimated radio continuum jet, and a massive molecular outflow.