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Paper: Feedback Effects in the High Mass and Low Mass Star Formation
Volume: 429, Numerical Modeling of Space Plasma Flows, Astronum-2009
Page: 97
Authors: Klein, R. I.
Abstract: The formation of massive stars remains one of the most significant unsolved problems in astrophysics, with implications for the formation of the elements and the structure and evolution of galaxies. It is these stars, with masses greater than 8-10 solar masses, that eventually explode as supernovae and produce most of the heavy elements in the universe, dominate the energy injection into the interstellar medium of galaxies and by injecting both heavy elements and energy into the surrounding medium, shape the evolution of galaxies. Despite the importance of massive star formation, relatively little is known about them theoretically as they pose a major theoretical challenge: How is it possible to sustain a sufficiently high mass accretion rate into a protostellar core despite the radiation pressure on the accreting envelope? I discuss our work on the first 3D simulations of massive star formation. Using our high resolution 3D radiation-hydrodynamic adaptive mesh refinement code ORION with a v/c correct treatment of the radiation transport, we have investigated the formation of high mass stars from both smooth and turbulent initial conditions in the collapsing massive core. I discuss our work on identifying 2 new mechanisms that efficiently solve the problem of the Eddington barrier to high mass star formation; the presence of 3D Rayleigh Taylor instabilities in radiation driven bubbles present in the accreting envelope and the feedback due to protostellar outflows providing radiation an escape mechanism from the accreting envelope in addition to the feedback from protostellar radiation and its affect on stellar multiplicity. I also discuss the effects of radiative transfer on low mass star formation in a turbulent molecular cloud. I compare the distribution of stellar masses, accretion rates, and temperatures in the cases with and without radiative transfer, and demonstrate that radiative feedback has profound effect on accretion, multiplicity, and mass by reducing the number of stars formed and the total rate at which gas turns into stars. Calculations that omit radiative feedback from protostars significantly underestimate the gas temperature and the strength of this effect.
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