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arXiv · 1610.03407

1.3mm polarized emission in the circumstellar disk of a massive protostar

M. Fernández-López·I. W. Stephens·J. M. Girart·L. Looney·S. Curiel·D. Segura-Cox·C. Eswaraiah·S. -P. Lai
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Abstract

We present the first resolved observations of the 1.3mm polarized emission from the disk-like structure surrounding the high-mass protostar Cepheus A HW2. These CARMA data partially resolve the dust polarization, suggesting an uniform morphology of polarization vectors with an average position angle of 57 degrees and an average polarization fraction of 2.0%. The distribution of the polarization vectors can be attributed to (1) the direct emission of magnetically aligned grains of dust by a uniform magnetic field, or (2) the pattern produced by the scattering of an inclined disk. We show that both models can explain the observations, and perhaps a combination of the two mechanisms produce the polarized emission. A third model including a toroidal magnetic field does not match the observations. Assuming scattering is the polarization mechanism, these observations suggest that during the first few 10000 years of high-mass star formation, grain sizes can grow from 1 to several 10s micron.

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M. Fernández-López, I. W. Stephens, J. M. Girart, L. Looney, S. Curiel, D. Segura-Cox, C. Eswaraiah, S. -P. Lai. 2016-10-11. 1.3mm polarized emission in the circumstellar disk of a massive protostar. https://doi.org/10.3847/0004-637x%2F832%2F2%2F200

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