SYNTHETIC OBSERVATIONS OF MAGNETIC FIELDS IN PROTOSTELLAR CORES

被引:33
|
作者
Lee, Joyce W. Y. [1 ,2 ]
Hull, Charles L. H. [1 ,4 ]
Offner, Stella S. R. [3 ]
机构
[1] Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
[2] Univ Southampton, Dept Phys & Astron, Univ Rd, Southampton SO17 1BJ, Hants, England
[3] Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA
[4] Natl Radio Astron Observ, Hancock, NH USA
来源
ASTROPHYSICAL JOURNAL | 2017年 / 834卷 / 02期
关键词
jets and outflows; ISM: magnetic fields; magnetohydrodynamics (MHD); polarization; stars: formation; stars: protostars; POLARIZED DUST EMISSION; MASSIVE STAR-FORMATION; MOLECULAR CLOUD CORES; DISK FORMATION; BRAKING CATASTROPHE; HYDRODYNAMIC SIMULATIONS; RADIATIVE-TRANSFER; TURBULENT ORIGIN; FORMING CORES; DARK CLOUD;
D O I
10.3847/1538-4357/834/2/201
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The role of magnetic fields in the early stages of star formation is not well constrained. In order to discriminate between different star formation models, we analyze 3D magnetohydrodynamic simulations of low-mass cores and explore the correlation between magnetic field orientation and outflow orientation over time. We produce synthetic observations of dust polarization at resolutions comparable to millimeter-wave dust polarization maps observed by the Combined Array for Research in Millimeter-wave Astronomy and compare these with 2D visualizations of projected magnetic field and column density. Cumulative distribution functions of the projected angle between the magnetic field and outflow show different degrees of alignment in simulations with differing mass-to-flux ratios. The distribution function for the less magnetized core agrees with observations finding random alignment between outflow and field orientations, while the more magnetized core exhibits stronger alignment. We find that fractional polarization increases when the system is viewed such that the magnetic field is close to the plane of the sky, and the values of fractional polarization are consistent with observational measurements. The simulation outflow, which reflects the underlying angular momentum of the accreted gas, changes direction significantly over over the first similar to 0.1 Myr of evolution. This movement could lead to the observed random alignment between outflows and the magnetic fields in protostellar cores.
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页数:13
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