Gravitational fragmentation and the formation of brown dwarfs in stellar clusters

By Ian A. Bonnell, P. C. Clark, Matthew R. Bate. 2008

139 citations recorded by the source corpus.

We investigate the formation of brown dwarfs and very low mass stars through the gravitational fragmentation of infalling gas into stellar clusters. The gravitational potential of a forming stellar cluster provides the focus that attracts gas from the surrounding molecular cloud. Structures present in the gas grow, forming filaments flowing into the cluster centre. These filaments attain high gas densities due to the combination of the cluster potential and local self-gravity. The resultant Jeans masses are low, allowing the formation of very low mass fragments. The tidal shear and high-velocity dispersion present in the cluster preclude any subsequent accretion, thus resulting in the formation of brown dwarfs or very low mass stars. Ejections are not required as the brown dwarfs enter the cluster with high relative velocities, suggesting that their disc and binary properties should be similar to that of low-mass stars. This mechanism requires the presence of a strong gravitational potential due to the stellar cluster implying that brown-dwarf formation should be more frequent in stellar clusters than in distributed populations of young stars. Brown dwarfs formed in isolation would require another formation mechanism such as due to turbulent fragmentation.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/2d06649c27ff942e93de51cf13f9d19d6ab6ad39

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Citations in the corpus

Radial variations in the stellar initial mass function of early-type galaxies (2014, background): “…thermal properties of the gas; the contribution of dust to cooling; magnetic fields; turbulence; the effect of supersonic motions in the turbulent gas; and the transition from pre-stellar cores to stars, among others (Padoan & Nordlund 2002; Larson 2005; Bonnell et al. 2008; Hopkins 2013).”
Physical Processes in the Interstellar Medium (2014, background): “is a chance that low-mass protostars collide and so successively build up more massive objects (Bonnell et al. 1998).”
On the fraction of star formation occurring in bound stellar clusters (2012, methodology): “Left-hand panel: local CFE γ as a function of the local SFE in the Bonnell et al. (2008) simulation.”
ANALYTICAL THEORY FOR THE INITIAL MASS FUNCTION. II. PROPERTIES OF THE FLOW (2009, background): “Indeed, the role of gravitational focussing in the production of brown dwarfs has been explicitly investigated by Bonnell et al. (2008).”
The dynamical state of stellar structure in star‐forming regions (2011, methodology): “Ideally, the next step would be to perform the same type of calculation as in Bonnell et al. (2008) for different initial conditions, including descriptions for radiative and mechanical feedback, potentially accounting for magnetic fields, and varying the sink particle radius.”