The Astronomical Journal | VOL. 120
Read
2MASS Observations of the Perseus, Orion A, Orion B, and Monoceros R2 Molecular Clouds
Abstract
We use the 2MASS Second Incremental Release Point Source Catalog to investigate the spatial distribution of young stars in the Perseus, Orion A, Orion B, and MonR2 molecular clouds. After subtracting a semiempirical model of the field star contamination from the observed star counts, stellar surface density maps are used to identify compact clusters and any stellar population found more uniformly distributed over the molecular cloud. Each cloud contains between two and seven clusters, with at least half of the cluster population found in a single, rich cluster. In addition, a distributed stellar population is inferred in the Orion A and MonR2 molecular clouds within the uncertainties of the field star subtraction with a surface density between 0.013 and 0.083 arcmin-2. Sensitivity calculations suggest, however, that the number of stars in the distributed population may be underestimated by a factor of 2 or more if stars have been forming with a Miller-Scalo IMF at a constant star formation rate for longer than 10 Myr. After considering the possible evolutionary status of the distributed population, the global star formation efficiency implied by the sum of the distributed and cluster populations ranges between 1% and 9% among the four clouds. The fraction of the total stellar population contained in clusters for the nominal extinction model ranges from ≈50% to 100% if the distributed population is relatively young (<10 Myr), to ≈25%–70% if it is relatively old (≈100 Myr). The relatively high fraction of stars contained in cl...
Round-ups are the summaries of handpicked papers around trending topics published every week. These would enable you to scan through a collection of papers and decide if the paper is relevant to you before actually investing time into reading it.
Climate change Research Articles published between Jun 20, 2022 to Jun 26, 2022
One eighth of the bird species in the world is considered globally threatened; the avifauna of Iraq comprises 409 species and is considered as the maj...
Read More