The JCMT Gould Belt Survey: A First Look at IC 5146
American Astronomical Society / IOP Publishing
We present 450 and 850 μm submillimeter continuum observations of the IC 5146 star-forming region taken as part of the James Clerk Maxwell Telescope Gould Belt Survey. We investigate the location of bright submillimeter (clumped) emission with the larger-scale molecular cloud through comparison with extinction maps, and find that these denser structures correlate with higher cloud column density. Ninety-six individual submillimeter clumps are identified using FellWalker, and their physical properties are examined. These clumps are found to be relatively massive, ranging from 0.5 M⊙ to 116 M⊙ with a mean mass of 8 M⊙ and a median mass of 3.7 M⊙ . A stability analysis for the clumps suggests that the majority are (thermally) Jeans stable, with M/Mj < 1. We further compare the locations of known protostars with the observed submillimeter emission, finding that younger protostars, i.e., Class 0 and I sources, are strongly correlated with submillimeter peaks and that the clumps with protostars are among the most Jeans unstable. Finally, we contrast the evolutionary conditions in the two major star-forming regions within IC 5146: the young cluster associated with the Cocoon Nebula and the more distributed star formation associated with the Northern Streamer filaments. The Cocoon Nebula appears to have converted a higher fraction of its mass into dense clumps and protostars, the clumps are more likely to be Jeans unstable, and a larger fraction of these remaining clumps contain embedded protostars. The Northern Streamer, however, has a larger number of clumps in total and a larger fraction of the known protostars are still embedded within these clumps.
Doug Johnstone is supported by the National Research Council of Canada and by an NSERC Discovery Grant. Steve Mairs was partially supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada graduate scholarship program. S.C., D.J., and H.K. thank Herzberg Astronomy and Astrophysics at the National Research Council of Canada for making this project possible through their co-op program.
This is the final version of the article. Available from IOP Publishing via the DOI in this record.
Vol. 836 (1), article 132