The Molecular Envelope around the Red Supergiant VY CMa

We present millimeter interferometric observations of the molecular envelopearound the red supergiant VY CMa with the SubMillimeter Array (SMA). The highangular resolution (< 2'') allows us to derive the structure of the envelope asobserved in the 1.3 mm continuum, 12CO(2-1), 13CO(2-1) and SO(6,5-5,4) linesemission. The circumstellar envelope is resolved into three components: adense, compact and dusty central component, embedded in a more diffuse andextended envelope plus a high velocity component. We construct a simple model,consisting of a spherically symmetric slowly expanding envelope and bipolaroutflows with a wide opening angle (~ 120 deg.) viewed close to the line ofsight (i = 15 deg.). Our model can explain the main features of the SMA dataand previous single-dish CO multi-line observations. An episode of enhancedmass loss along the bipolar direction is inferred from our modelling. The SMAdata provide a better understanding of the complicated morphology seen in theoptical/IR high resolution observations.Comment: accepted for publication in Ap