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J. C. Tan (Astronomy Dept., UC Berkeley; Astrophysical Sciences Dept., Princeton University), C. F. McKee (Physics & Astronomy Depts., UC Berkeley)
We model the formation of high-mass stars, specifying the accretion rate in terms of the instantaneous and final mass of the star, the ambient pressure of the star-forming region and the form of polytropic pressure support of the pre-stellar gas core. The high pressures typical of Galactic regions of massive star formation allow a 100\:{\rm M\odot} star to form in ~105\:{\rm yr} with a final accretion rate ~10-3\:{\rm M\odot\:yr-1}. By modeling protostellar evolution, we predict the properties of several nearby massive protostars. We include ionizing feedback to examine the implications of this model for the lifetimes and electron densities of hyper-compact HII regions.
By applying our star formation model to many stars, we investigate star cluster formation. The observed intensity of outflows from protoclusters is used to estimate the star formation rate. We find clusters take at least several free-fall times to form. Finally, we examine the role of feedback processes in determining the star formation efficiency of clusters as a function of their initial gas mass and density.