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Séminaire du Jeudi 26 Janvier 2012

Early phases of star formation : study of prestellar core collapse using radiation-magneto-hydrodynamic calculations

Benoît Commerçon (LERMA)
Jeudi 26 Janvier - 11 h 00
Salle Manuel Forestini - IPAG

Stars are the main source of luminous matter in the Universe. By transforming gas and tiny dust particles into stars, star formation is a dominant process in the interstellar cycle. In addition, star formation is also crucial to understand planet formation and it shapes the evolution and the structure of galaxies. Consequently, it is of prime importance in astrophysics to understand how stars form. Although it is well established that stars form within molecular clouds via gravitational collapse, their formation remains poorly understood. Star formation indeed involves multi-scales and highly non-linear processes which are complex to model. In this context, I will present original radiation-magneto-hydrodynamics calculations of low-mass and massive dense core collapse, focusing on the first collapse and the first hydrostatic core (first Larson core) formation. In a first part reporting, I will investigate the combined feedback of radiative transfer and magnetic fields on the collapse and fragmentation of low-mass dense cores. Then, I will present synthetic spectral energy distributions and ALMA dust emission maps predictions, as well as classical observational quantities such as the bolometric temperature and luminosity. I will show how the dust continuum can help to target first hydrostatic cores and to state about the nature of VeLLOs. Last, I will present synthetic ALMA observation predictions of first hydrostatic cores which may give an answer, if not definitive, to the fragmentation issue at the early Class 0 stage. In a second part, I will report recent results in the context of high mass star formation (Commercon, Hennebelle and Henning ApJL 2011). In this study, we investigate the combined effects of magnetic field, turbulence, and radiative transfer on the early phases of the collapse and the fragmentation of massive dense cores (M=100 Msun). We identify a new mechanism that inhibits initial fragmentation of massive dense cores, where magnetic field and radiative transfer interplay.. We speculate that highly magnetized massive dense cores are good candidates for isolated massive star formation, while moderately magnetized massive dense cores are more appropriate to form OB associations or small star clusters.

Présentation MOV

Sous la tutelle de:


Sous la tutelle de:

CNRS Université Grenoble Alpes