High angular resolution millimetre continuum observations and modelling of S140-IRS1

We present high-resolution 1.3mmcontinuum observations of themassive young stellar object S140-IRS1. S140-IRS1 is adisc wind prototype with elongated radio emission (PA ~ 45°) perpendicular to the large-scale CO outflow in the region. The observations taken with the CARMA B array and the Submillimetre Array (SMA) compact configuration correspond to a spatial resolution of 0.3 and 3.0 arcsec, respectively. Complementary 2.7 and 3.5mmdata taken with OVRO in a compact configuration are also discussed. The deconvolved position angle for S140-IRS1 of 37° ±15° is compatible with a disc perpendicular to the main CO outflow and near-infrared monopolar reflection nebula. We have utilized two-dimensional axisymmetric radiative transfer modelling to interpret the millimetre wave emission from S140-IRS1. The model required the additionof a disc component, as the observed image, flux and visibilities cannot be represented solely by a dusty envelope with polar cavities. We report that the highresolution image of S140-IRS1 is consistent with the interpretation of emission from a dust disc in a large-scale envelope with cleared bipolar cavities. Strong continuum emission is also detected in both SMA and OVRO maps from the previously discovered submillimetre source S140-SMM1 and from the infrared source S140-IRS3. Furthermore, S140-SMM1 is identified with maser sources whose proper motions are consistent with being the source ofthe outflow with position angle ~20° previously associated by some authors with a second outflow created by S140-IRS1. Our findings are consistent with a disc wind interpretation of the radio emission for S140-IRS1 rather than that of a jet. © 2012 The Authors.