We present millimeter interferometric observations of the molecular envelope around the red supergiant VY CMa with the SubMillimeter Array (SMA). The high angular resolution (< 2'') allows us to derive the structure of the envelope as observed in the 1.3 mm continuum, 12CO(2-1), 13CO(2-1) and SO(6,5-5,4) lines emission. The circumstellar envelope is resolved into three components: a dense, compact and dusty central component, embedded in a more diffuse and extended envelope plus a high velocity component. We construct a simple model, consisting of a spherically symmetric slowly expanding envelope and bipolar outflows with a wide opening angle (~ 120 deg.) viewed close to the line of sight (i = 15 deg.). Our model can explain the main features of the SMA data and previous single-dish CO multi-line observations. An episode of enhanced mass loss along the bipolar direction is inferred from our modelling. The SMA data provide a better understanding of the complicated morphology seen in the optical/IR high resolution observations.
@article{arxiv.astro-ph/0611547,
title = {The molecular envelope around the red supergiant VY CMa},
author = {S. Muller and Dinh-V-Trung and J. Lim and N. Hirano and C. Muthu and S. Kwok},
journal= {arXiv preprint arXiv:astro-ph/0611547},
year = {2008}
}