Arcsecond resolution mapping of Sulfur Dioxide emission in the circumstellar envelope of VY Canis Majoris

Abstract

We report Submillimeter Array observations of SO2 emission in the circumstellar envelope of the red supergiant VY CMa, with an angular resolution of ~1". SO2 emission appears in three distinct outflow regions surrounding the central continuum peak emission that is spatially unresolved. No bipolar structure is noted in the sources. A fourth source of SO2 is identified as a spherical wind centered at the systemic velocity. We estimate the SO2 column density and rotational temperature assuming local thermal equilibrium (LTE) as well as perform non-LTE radiative transfer analysis using RADEX. Column densities of SO2 are found to be ~10^16 cm^-2 in the outflows and in the spherical wind. Comparison with existing maps of the two parent species OH and SO shows the SO2 distribution to be consistent with that of OH. The abundance ratio f_SO2/f_SO is greater than unity for all radii greater than at least 3x10^16 cm. SO2 is distributed in fragmented clumps compared to SO, PN, and SiS molecules. These observations lend support to specific models of circumstellar chemistry that predict f_SO2/f_SO>1 and may suggest the role of localized effects such as shocks in the production of SO2 in the circumstellar envelope.

Accepted for publication in ApJ

References in corpus (5)

• Red supergiants as potential Type IIn supernova progenitors: Spatially resolved 4.6 micron CO emission around VY CMa and Betelgeuse
• The 3D Morphology of VY Canis Majoris. I The Kinematics of the Ejecta
• The molecular envelope around the red supergiant VY CMa
• Bringing VY Canis Majoris Down to Size: An Improved Determination of Its Effective Tempeature
• A red supergiant nebula at 25 micron: arcsecond scale mass-loss asymmetries of mu Cep

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• ALMA Observations of the massive molecular outflow G331.512-0.103 II: physical properties, kinematics, and geometry modeling