Formation of low-mass stars and brown dwarfs

Abstract

These lectures attempt to expose the most important ideas, which have been proposed to explain the formation of stars with particular emphasis on the formation of brown dwarfs and low-mass stars. We first describe the important physical processes which trigger the collapse of a self-gravitating piece of fluid and regulate the star formation rate in molecular clouds. Then we review the various theories which have been proposed along the years to explain the origin of the stellar initial mass function paying particular attention to four models, namely the competitive accretion and the theories based respectively on stopped accretion, MHD shocks and turbulent dispersion. As it is yet unsettled whether the brown dwarfs form as low-mass stars, we present the theory of brown dwarfs based on disk fragmentation stressing all the uncertainties due to the radiative feedback and magnetic field. Finally, we describe the results of large scale simulations performed to explain the collapse and fragmentation of molecular clouds.

proceedings of the Evry Schatzman School on "Low-mass stars and the transition between stars and brown dwarfs" (Roscoff 2011), to appear in EAS Publication Series (Eds C.Reylé, C.Charbonnel, & M.Schultheis)

References in corpus (26)

• Theory of Star Formation
• The Statistics of Supersonic Isothermal Turbulence
• Analytical theory for the initial mass function: CO clumps and prestellar cores
• Stellar, brown dwarf and multiple star properties from a radiation hydrodynamical simulation of star cluster formation
• Modeling Collapse and Accretion in Turbulent Gas Clouds: Implementation and Comparison of Sink Particles in AMR and SPH
• Radiation-Hydrodynamic Simulations of Collapse and Fragmentation in Massive Protostellar Cores
• The Burst Mode of Protostellar Accretion
• The properties of brown dwarfs and low-mass hydrogen-burning stars formed by disc fragmentation
• The Effects of Radiative Transfer on Low-Mass Star Formation
• Magnetic processes in a collapsing dense core. I Accretion and Ejection
• The Importance of Radiative Feedback for the Stellar Initial Mass Function
• Analytical star formation rate from gravoturbulent fragmentation
• Magnetic Braking and Protostellar Disk Formation: The Ideal MHD Limit
• The impact of magnetic fields on single and binary star formation
• Numerical simulations of compressively driven interstellar turbulence: I. Isothermal gas
• From the warm magnetized atomic medium to molecular clouds
• Collapse of massive magnetized dense cores using radiation-magneto-hydrodynamics: early fragmentation inhibition
• Magnetic processes in a collapsing dense core. II Fragmentation. Is there a fragmentation crisis ?
• Gravitational fragmentation and the formation of brown dwarfs in stellar clusters
• The minimum mass for star formation, and the origin of binary brown dwarfs
• Gravitational collapse of magnetized clouds. I. Ideal MHD accretion flow
• Formation Scenario for Wide and Close Binary Systems
• On the Constancy of the Characteristic Mass of Young Stars
• Clump Lifetimes and the Initial Mass Function
• The structure of molecular clouds and the universality of the clump mass function
• Dimensional argument for the impact of turbulent support on the stellar initial mass function

Cited by in corpus (2)

• Spectroscopy of brown dwarf candidates in IC 348 and the determination of its substellar IMF down to planetary masses
• Dust cleansing of star-forming gas: II. Did late accretion flows change the chemical composition of the solar atmosphere?