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M. R. Krumholz, C. F. McKee (UC Berkeley), R. I. Klein (UC Berkeley and LLNL)
We present simulations and analytic work showing that the effectiveness of radiation pressure in inhibitinig the formation of massive stars has been greatly overestimated. Radiation pressure likely presents no significant barrier to massive star formation, despite the fact that the luminosity of a massive star can greatly exceed the Eddington limit for continued accretion.
Stars with masses above ~20 solar masses have short Kelvin times that enable them to reach the main sequence while still accreting from their natal clouds. As a result, they produce a huge luminosity that can exert a radiation pressure force on dust grains suspended in the accreting gas that is stronger than gravity. We show, however, that despite its strength the radiation is unable to stop accretion. Radiation-driven bubbles that block accreting gas are subject to Rayleigh-Taylor instability, which allows fingers of dense gas to break into the evacuated bubbles and reach the stellar surface. In addition, outflows from massive stars create optically thin cavities in the accreting envelope. These channel radiation away from the bulk of the gas and reduce the radiation pressure it experiences. The discovery of these two mechanisms implies that radiation pressure feedback is not the dominant factor in setting the final size of massive stars.
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The author(s) of this abstract have provided an email address for comments about the abstract: krumholz@astron.berkeley.edu
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.