An Equatorial Wind from the Massive Young Stellar Object S140 IRS 1

Abstract

The discovery of the second equatorial ionized stellar wind from a massive young stellar object is reported. High-resolution radio continuum maps of S140 IRS 1 reveal a highly elongated source that is perpendicular to the larger scale bipolar molecular outflow. This picture is confirmed by location of a small-scale monopolar near-IR reflection nebula at the base of the blueshifted lobe. A second epoch of observations over a 5 yr baseline show little ordered outward proper motion of clumps as would have been expected for a jet. A third epoch, taken only 50 days after the second, did show significant changes in the radio morphology. These radio properties can all be understood in the context of an equatorial wind driven by radiation pressure from the central star and inner disk acting on the gas in the surface layers of the disk as proposed by Drew et al. This equatorial wind system is briefly compared with the one in S106 IR, and contrasted with other massive young stellar objects that drive ionized jets.