CLUSTERED STAR FORMATION IN MAGNETIC CLOUDS: PROPERTIES OF DENSE CORES FORMED IN OUTFLOW-DRIVEN TURBULENCE

Journal Article · Mon Oct 10 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/740/1/36; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21587418

Nakamura, Fumitaka ^[1]

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1. National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan)

We investigate the physical properties of dense cores formed in turbulent, magnetized, parsec-scale clumps of molecular clouds, using three-dimensional numerical simulations that include protostellar outflow feedback. The dense cores are identified in the simulated density data cube through a clumpfind algorithm. We find that the core velocity dispersion does not show any clear dependence on the core size, in contrast to Larson's linewidth-size relation, but consistent with recent observations. In the absence of a magnetic field, the majority of the cores have supersonic velocity dispersions. A moderately strong magnetic field reduces the dispersion to a subsonic or at most transonic value typically. Most of the cores are out of virial equilibrium, with the external pressure dominating the self-gravity. The implication is that the core evolution is largely controlled by the outflow-driven turbulence. Even an initially weak magnetic field can retard star formation significantly, because the field is amplified by the outflow-driven turbulence to an equipartition strength, with the distorted field component dominating the uniform one. In contrast, for a moderately strong field, the uniform component remains dominant. Such a difference in the magnetic structure is evident in our simulated polarization maps of dust thermal emission; it provides a handle on the field strength. Recent polarization measurements show that the field lines in cluster-forming clumps are spatially well ordered. It is indicative of a moderately strong, dynamically important field which, in combination with outflow feedback, can keep the rate of star formation in embedded clusters at the observationally inferred, relatively slow rate of several percent per free-fall time.

• OSTI ID: 21587418
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 740; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CLOUDS
COMPUTERIZED SIMULATION
DENSITY
FLUID MECHANICS
HYDRODYNAMICS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MECHANICS
PHYSICAL PROPERTIES
POLARIZATION
SIMULATION
STAR CLUSTERS
THREE-DIMENSIONAL CALCULATIONS
TURBULENCE
VELOCITY