Collapse, outflows and fragmentation of massive, turbulent and magnetized prestellar barotropic cores

By P. Hennebelle, B. Commerçon, M. Joos, Ralf Klessen, Mark R. Krumholz, Jonathan C. Tan, Romain Teyssier. 2011

142 citations recorded by the source corpus.

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.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/1bb5e22d69c2e16ac902d27eea71dacaee63d1b2

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Citations in the corpus

COLLAPSE OF MASSIVE MAGNETIZED DENSE CORES USING RADIATION MAGNETOHYDRODYNAMICS: EARLY FRAGMENTATION INHIBITION (2011, methodology): “To visualize the difference between our work and other studies, we overplot the barotropic law that is used in Hennebelle et al. (2011).”
Physical Processes in the Interstellar Medium (2014, background): “It can alter how cores fragment (Price & Bate, 2007b, 2008; Hennebelle & Fromang, 2008; Hennebelle & Teyssier, 2008; Hennebelle et al., 2011; Peters et al., 2011), change the coupling between stellar feedback processes and their parent clouds (Nakamura & Li, 2007; Krumholz et al.”
Protostellar disk formation and transport of angular momentum during magnetized core collapse (2012, background): “It is therefore unlikely that the Alfvén speed drops with radius as 1/r, and collapse calculations indeed show that the Alfvén speed remains roughly constant in the dense cores (e.g. Hennebelle et al. 2011).”
LOW VIRIAL PARAMETERS IN MOLECULAR CLOUDS: IMPLICATIONS FOR HIGH-MASS STAR FORMATION AND MAGNETIC FIELDS (2013, background): “…conditions numerical cloud simulations with initial virial parameters α > 1 (e.g., series of simulations started by Bate et al. 2002) or α < 1 (e.g., Hennebelle et al. 2011) may apply, and why some stellar clusters might be born with velocity dispersions too low to balance self–gravity (see…”
THE STAR FORMATION RATE OF TURBULENT MAGNETIZED CLOUDS: COMPARING THEORY, SIMULATIONS, AND OBSERVATIONS (2012, background): “…molecular clouds, magnetic fields seem to reduce fragmentation significantly (see Figure 4), thus potentially having a strong impact on the mass distribution of cores and stars (see also Price & Bate 2007; Hennebelle & Teyssier 2008; Bürzle et al. 2011; Peters et al. 2011; Hennebelle et al. 2011).”
FORMATION OF MASSIVE MOLECULAR CLOUD CORES BY CLOUD–CLOUD COLLISION (2013, background): “However, Peters et al. (2011) and Hen- nebelle et al. (2011) showed that the level of fragmentation is reduced typically only by a factor of 2.”
Importance of the Initial Conditions for Star Formation - I. Cloud Evolution and Morphology (2010, background): “Banerjee et al. (2009), Peters et al. (2011) and Hennebelle et al. (2011) noted reduced fragmentation in high-mass cores.”
NON-IDEAL MHD EFFECTS AND MAGNETIC BRAKING CATASTROPHE IN PROTOSTELLAR DISK FORMATION (2011, background): “A potential concern is that the misalignment increases the flow complexity, which may enhance the numerical magnetic diffusion that is considerable on small scales (see a nice discussion in §5.3 of Hennebelle et al. 2011).”