Lowering the Characteristic Mass of Cluster Stars by Magnetic Fields and Outflow Feedback

Abstract

Magnetic fields are generally expected to increase the characteristic mass of stars formed in stellar clusters, because they tend to increase the effective Jeans mass. We test this expectation using adaptive mesh refinement (AMR) magnetohydrodynamic simulations of cluster formation in turbulent magnetized clumps of molecular clouds, treating stars as accreting sink particles. We find that, contrary to the common expectation, a magnetic field of strength in the observed range decreases, rather than increases, the characteristic stellar mass. It (1) reduces the number of intermediate-mass stars that are formed through direct turbulent compression, because sub-regions of the clump with masses comparable to those of stars are typically magnetically subcritical and cannot be compressed directly into collapse, and (2) increases the number of low-mass stars that are produced from the fragmentation of dense filaments. The filaments result from mass accumulation along the field lines. In order to become magnetically supercritical and fragment, the filament must accumulate a large enough column density (proportional to the field strength), which yields a high volume density (and thus a small thermal Jeans mass) that is conducive to forming low-mass stars. We find, in addition, that the characteristic stellar mass is reduced further by outflow feedback. The conclusion is that both magnetic fields and outflow feedback are important in shaping the stellar initial mass function (IMF).

Accepted to ApJL

References in corpus (8)

• Theory of Star Formation
• Analytical theory for the initial mass function: CO clumps and prestellar cores
• 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 Effects of Radiative Transfer on Low-Mass Star Formation
• The Jeans mass and the origin of the knee in the IMF
• Fragmentation and Evolution of Molecular Clouds. II: The Effect of Dust Heating
• Protostar Mass Due to Infall and Dispersal

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