The Lifetimes of Massive Star-Forming Regionssu201714 | www.cfa.harvard.edu/
https://www.cfa.harvard.edu/news/su201714
Astronomers can roughly estimate how long it takes for a new star to form: it is the time it takes for material in a gas cloud to collapse in free-fall,
and is set by the mass, the size of the cloud, and gravity. Although an approximation, this scenario of quick, dynamic star formation is consistent with
many observations, especially of sources where new material can flow into the cloud, perhaps along filaments, to sustain steady activity. But this simple
picture might not apply in the largest systems with star clusters and high-mass stars. Rather than a quick collapse, the process there might be inhibited
by pressure, turbulence, or other activities that slow it down.
CfA astronomer Cara Battersby and two colleagues studied the formation, early evolution, and lifetimes of high-mass star-forming regions and their earliest
evolutionary phases in dense, molecular regions. These clumps have densities of gas as high as ten million molecules per cubic centimeter (tens of thousands
of times higher than typical in gas clouds); the dust associated with this gas blocks the external starlight, leaving the material very cold, only a few tens
of degrees above absolute zero. The usual method for identifying these clumps is with submillimeter telescopes, which take images of the sky; automated
algorithms can then process the images to identify and characterize cold clumps. The problem is that even a quiescent clump can contain subregions of activity
that are not spotted with the relatively poor spatial resolutions of the submillimeter telescopes used to assemble catalogs of these regions.
