期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 702, 期 1, 页码 L37-L41出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/702/1/L37
关键词
ISM: magnetic fields; MHD; radiative transfer; stars: formation
资金
- NASA [NNG056601G]
- NSF [AST-0507768]
- Danish Natural Science Research Council
- Academy of Finland [124620, 105623]
- Vaisala foundation
- Academy of Finland (AKA) [105623, 124620, 124620, 105623] Funding Source: Academy of Finland (AKA)
Recent measurements of the Zeeman effect in dark-cloud cores provide important tests for theories of cloud dynamics and prestellar core formation. In this Letter, we report results of simulated Zeeman measurements, based on radiative transfer calculations through a snapshot of a simulation of supersonic and super-Alfvenic turbulence. We have previously shown that the same simulation yields a relative mass-to-flux ratio (core versus envelope) in agreement with the observations (and in contradiction with the ambipolar-drift model of core formation). Here, we show that the mass-to-flux and turbulent-to-magnetic-energy ratios in the simulated cores agree with the observed values as well. The mean magnetic field strength in the simulation is very low, (B) over bar = 0.34 mu G, presumably lower than the mean field in molecular clouds. Nonetheless, high magnetic field values are found in dense cores, in agreement with the observations (the rms field, amplified by the turbulence, is B(rms) = 3.05 mu G). We conclude that a strong large-scale mean magnetic field is not required by Zeeman effect measurements to date, although it is not ruled out by this work.
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