Journal
ASTRONOMY & ASTROPHYSICS
Volume 528, Issue -, Pages -Publisher
EDP SCIENCES S A
DOI: 10.1051/0004-6361/201016052
Keywords
magnetohydrodynamics (MHD); instabilities; ISM: kinematics and dynamics; ISM: clouds; stars: formation
Categories
Funding
- Institut des sciences de l'univers (CNRS)
- German Bundesministerium fur Bildung und Forschung
- Baden-Wurttemberg Stiftung [P-LS-SPII/18]
- Deutsche Forschungsgemeinschaft (DFG) [KL 1358/1, KL 1358/4, KL 1359/5, KL 1358/10, KL 1358/11]
- Heidelberg University
- German Excellence Initiative
- Alfred P. Sloan Fellowship
- US National Science Foundation [AST-0807739, CAREER-0955300]
- NASA through Astrophysics Theory and Fundamental Physics [NNX09AK31G]
- Max-Planck-Institut fur Astronomie
- NSF [AST-0645412]
- NASA Astrophysics Theory and Fundamental Physics [ATP09-0094]
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [0807739] Funding Source: National Science Foundation
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Context. Stars, and more particularly massive stars, have a drastic impact on galaxy evolution. Yet the conditions in which they form and collapse are still not fully understood. Aims. In particular, the influence of the magnetic field on the collapse of massive clumps is relatively unexplored, it is therefore of great relevance in the context of the formation of massive stars to investigate its impact. Methods. We perform high resolution, MHD simulations of the collapse of one hundred solar masses, turbulent and magnetized clouds, with the adaptive mesh refinement code RAMSES. We compute various quantities such as mass distribution, magnetic field, and angular momentum within the collapsing core and study the episodic outflows and the fragmentation that occurs during the collapse. Results. The magnetic field has a drastic impact on the cloud evolution. We find that magnetic braking is able to substantially reduce the angular momentum in the inner part of the collapsing cloud. Fast and episodic outflows are being launched with typical velocities of the order of 1-3 km s(-1), although the highest velocities can be as high as 20-40 km s(-1). The fragmentation in several objects is reduced in substantially magnetized clouds with respect to hydrodynamical ones by a factor of the order of 1.5-2. Conclusions. We conclude that magnetic fields have a significant impact on the evolution of massive clumps. In combination with radiation, magnetic fields largely determine the outcome of massive core collapse. We stress that numerical convergence of MHD collapse is a challenging issue. In particular, numerical diffusion appears to be important at high density and therefore could possibly lead to an overestimation of the number of fragments.
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