Mon. Not. R. Astron. Soc., 428, 609-624 (2013/January-1)
High angular resolution millimetre continuum observations and modelling of S140-IRS1.
MAUD L.T., HOARE M.G., GIBB A.G., SHEPHERD D. and INDEBETOUW R.
Abstract (from CDS):
We present high-resolution 1.3 mm continuum observations of the massive young stellar object S140-IRS1. S140-IRS1 is a disc 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 3.5 mm data 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 addition of 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 high-resolution 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 of the 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.