Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 1H007

Simulations Of Protostellar Collapse Using Multigroup Radiation Hydrodynamics

Vaytet, Neil (Centre de Recherche Astrophysique de Lyon, ENS Lyon, France)
Chabrier, Gilles (Centre de Recherche Astrophysique de Lyon, ENS Lyon, France; School of Physics, University of Exeter, UK)
Audit, Edouard (Maison de la Simulation, CEA Saclay, France; Service d’Astrophysique, CEA Saclay, France)
Commercon, Benoit (Laboratoire de radioastronomie, ENS Paris, France)
Masson, Jacques (Centre de Recherche Astrophysique de Lyon, ENS Lyon, France)

Star formation begins with the gravitational collapse of a dense core inside a molecular cloud. As the collapse progresses, the centre of the core begins to heat up as it becomes optically thick. The temperature and density in the centre eventually reach high enough values where fusion reactions can ignite; the protostar is born. This sequence of events entails many physical processes, of which radiative transfer is of paramount importance. Many simulations of protostellar collapse make use of a grey treatment of radiative transfer coupled to the hydrodynamics. However, interstellar gas and dust opacities present large variations as a function of frequency, which can be overlooked by grey models and lead to significantly different results. In this work, we perform simulations of the first and second phases of the collapse leading to the formation of the first and second Larson cores using multigroup radiation hydrodynamics. We have adopted a non-ideal gas equation of state as well as an extensive set of spectral opacities in a spherically symmetric code to model all the phases of the collapse of a 0.1, 1 and 10 solar mass cloud cores. We find that the first core accretion shock remains supercritical while the shock at the second core border is strongly subcritical with all the accreted energy being transfered to the core. The size of the first core was found to vary somewhat in the different simulations (more unstable clouds form smaller first cores) while the size, mass and temperature of the second cores are independent of initial cloud mass, size and temperature. Our simulations support the idea of astandard (universal) initial second core size and mass.The grey approximation for radiative transfer appears to perform well in one-dimensional simulations of protostellar collapse, however the effects of using multigroup radiative transfer may be more important in the long term evolution of the protostar. Finally, we also present some early 3D results which were obtained using the AMR code RAMSES.

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