AMBIPOLAR DIFFUSION HEATING IN TURBULENT SYSTEMS

Journal Article · Tue Nov 20 04:00:00 EST 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/760/1/33· OSTI ID:22086333

Li, Pak Shing ^[1]; Myers, Andrew ^[2]

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1. Astronomy Department, University of California, Berkeley, CA 94720 (United States)
2. Physics Department, University of California, Berkeley, CA 94720 (United States)

The temperature of the gas in molecular clouds is a key determinant of the characteristic mass of star formation. Ambipolar diffusion (AD) is considered one of the most important heating mechanisms in weakly ionized molecular clouds. In this work, we study the AD heating rate using two-fluid turbulence simulations and compare it with the overall heating rate due to turbulent dissipation. We find that for observed molecular clouds, which typically have Alfven Mach numbers of {approx}1 and AD Reynolds numbers of {approx}20, about 70% of the total turbulent dissipation is in the form of AD heating. AD has an important effect on the length scale where energy is dissipated: when AD heating is strong, most of the energy in the cascade is removed by ion-neutral drift, with a comparatively small amount of energy making it down to small scales. We derive a relation for the AD heating rate that describes the results of our simulations to within a factor of two. Turbulent dissipation, including AD heating, is generally less important than cosmic-ray heating in molecular clouds, although there is substantial scatter in both.

• OSTI ID: 22086333
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 760; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AMBIPOLAR DIFFUSION
ASTRONOMY
ASTROPHYSICS
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
COSMIC RADIATION
HEATING
HEATING RATE
IONS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MASS
PLASMA FLUID EQUATIONS
REYNOLDS NUMBER
STARS
TURBULENCE