Chemical and Dynamical Evolution of Infrared Dark Clouds, Massive Protostars and Proto Star Clusters

Type Conference Paper
Names J. Tan, A. Hernandez, M. Butler, B. Ma, Y. Zhang, P. Barnes, S. O'Dougherty, P. Caselli, F. Fontani, I. Jimenez-Serra
Proceedings Title 280th Symposium of the International Astronomical Union
Conference Name The Molecular Universe
Place Toledo, Spain
Pages 347P
Date May 1, 2011
ISBN 1743-9221
Library Catalog
Abstract I briefly summarize several observational and theoretical results on the chemical and dynamical evolution of the gas and dust clouds that form massive stars and star clusters: 1) I review results from Mid-Infrared (MIR) (~3 to 70 micron) extinction mapping of Infrared Dark Clouds (IRDCs), which allow the initial conditions of massive star and star cluster formation to be probed in exquisite detail. We have found clear evidence for widespread depletion of CO molecules onto dust grains as a function of mass surface density. We have also found evidence for evolution of the MIR extinction law as a function of mass surface density, which is likely due to the formation of these molecular grain mantles. 2) These data also yield constraints on the dynamical state of the cores and clumps that we expect to be the initial conditions of massive stars and star clusters. I present results of theoretical models of massive star formation, including the evolution of the temperature and density structures around massive protostars and the implications for astrochemical models. 3) Finally, I briefly highlight results from the Census of High and Medium-mass Protostars (CHaMP), which is a large, unbiased survey of ~300 dense molecular clumps in the southern Milky Way (PI: Dr. Peter Barnes). These clumps have been mapped with the Mopra telescope in multiple molecular line transitions in the 90 and 110 GHz bands, including 12CO, 13CO, C18O, HCO+, H13CO+, HCN and N2H+. We find clear trends of chemical abundance evolution of these species with, for example, bolometric luminosity per unit gas mass.
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