The Evolution of Accreting Young Massive Objects
First Author:
Harold Yorke
Email: Harold.Yorke AT jpl.nasa.gov
Jet Propulsion Laboratory, Pasadena, CA
4800 Oak Grove Drive, MS 183-335
Pasadena, CA 91001 USA
Coauthors:
Abstract
Young stars and protostars gain much if not most of their mass via accretion through an accretion disk, starting with a low mass object (a few Jupiter masses) in hydrostatic equilibrium and gradually growing in mass as they accrete material. The time scale for this process is relatively short, typically less than several 100,000 yr, implying mass accretion rates in excess of 0.0001 Msun/yr for stars of 10 Msun and higher. Evolutionary tracks of accreting protostars are calculated and compared to those of non-accreting protostars. "Bloating" of stellar radii well in excess of 100 Rsun occurs after about 5 Msun have accreted; prior to the bloating the stellar radius is several Rsun. We find that the accretion luminosity of accreting protostars dominates during early phases (low stellar masses but with a small radius). The stellar luminosity dominates during the late accretion phases. Molecular core collapse case "F" (slowly rotating 10 Msun collapsing core) discussed by Yorke & Bodenheimer (1999) is recalculated using a modified version of the original 2D radiation-hydro code: Material flowing into the central zone is added to a spherically symmetric hydrostatic object whose evolution is simultaneously followed using a stellar evolution code.
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