LOWERING THE CHARACTERISTIC MASS OF CLUSTER STARS BY MAGNETIC FIELDS AND OUTFLOW FEEDBACK

Journal Article · Wed Sep 01 04:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/720/1/L26· OSTI ID:21452851

Zhiyun, Li ^[1]; Peng, Wang; Abel, Tom ^[2]; Nakamura, Fumitaka ^[3]

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1. Astronomy Department, P.O. Box 400325, University of Virginia, Charlottesville, VA 22904 (United States)
2. KIPAC, SLAC, and Physics Department, Stanford University, Menlo Park, CA 94025 (United States)
3. National Astronomical Observatory, Mikata, Tokyo 181-8588 (Japan)

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 magnetohydrodynamical 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 the 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.

• OSTI ID: 21452851
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 720; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
79 ASTRONOMY AND ASTROPHYSICS
FLUID MECHANICS
HYDRODYNAMICS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MECHANICS
SIMULATION
STAR CLUSTERS
STARS