1.3 mm 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

Research output: Contribution to journalArticlepeer-review

Abstract

We present the first resolved observations of the 1.3 mm polarized emission from the disk-like structure surrounding the high-mass protostar Cepheus A HW2. These CARMA data partially resolve the dust polarization, suggesting a uniform morphology of polarization vectors with an average position angle of 57° ± 6° and an average polarization fraction of 2.0% ± 0.4%. 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 produces 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 104 years of high-mass star formation, grain sizes can grow from1 mm to several 10s μm.

Original languageEnglish (US)
Article number200
JournalAstrophysical Journal
Volume832
Issue number2
DOIs
StatePublished - Dec 1 2016

Keywords

  • ISM: individual objects (Cepheus A HW2)
  • ISM: magnetic fields
  • polarization
  • stars: formation
  • techniques: polarimetric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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