S316p.37 — The Census of High- and Medium-mass Protostars (CHaMP): From Molecular Clouds to Massive Young Clusters

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Aug 10th at 6:00 PM until 7:30 PM

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Author(s): Peter Barnes1

Institution(s): 1. University of Florida

I review the major science outcomes to date of the Galactic Census of High- and Medium-mass Protostars, and also report the latest observational results on this unbiased, uniform sample of massive, cluster-forming molecular clumps, based on new mm-wave and IR data. These clouds represent the vast, subthermally-excited population of clumps predicted by Narayanan et al (2008) to dominate the molecular mass of disk galaxies. Besides confirming their existence, we have presented evidence that these massive clumps probably spend a large fraction (90-95%) of their long lives (possibly up to 100 Myr) in a mostly quiescent, low star formation rate (SFR) state, which is likely ended when a density or internal pressure threshold is crossed, after which vigorous, massive cluster formation consumes the densest gas with a high SFR, dispersing the embedding envelope. New results presented in two posters at this Symposium include (1) the first analysis of HCN emission from the dense gas using a full LTE solution for the column density from the hyperfine line ratios (Schap et al), which identifies low-luminosity but high-column areas that significantly increase the clumps' mass estimates, and (2) the first deep photometry of clusters in this sample based on NIR AAT and CTIO data and MIR Warm Spitzer IRAC data (Dallilar et al), which gives basic cluster parameters such as mass and luminosity as well as the associated star formation efficiency (SFE).