Molecular outflows in the substellar domain: Millimeter observations of young very low mass objects in taurus and ρ Ophiuchi

Abstract

We report here our search for molecular outflows from young very low mass stars and brown dwarfs in Taurus and ρ Ophiuchi. Using the Submillimeter Array and the Combined Array for Research in Millimeter-wave Astronomy, we have observed four targets at 1.3mm wavelength (230GHz) to search for CO J = 2 → 1 outflows. A young very low mass star MHO 5 (in Taurus) with an estimated mass of 90 M J, which is just above the hydrogen-burning limit, shows two gas lobes that are likely outflows. While the CO map of MHO 5 does not show a clear structure of outflow, possibly due to environment gas, its position-velocity diagram indicates two distinct blue- and redshifted components. We therefore conclude that they are components of a bipolar molecular outflow from MHO 5. We estimate an outflow mass of 7.0 × 10 -5 M and a mass-loss rate of 9.0 × 10-10 M . These values are over two orders of magnitude smaller than the typical ones for T Tauri stars and somewhat weaker than those we have observed in the young brown dwarf ISO-Oph 102 of 60 M J in ρ Ophiuchi. This makes MHO 5 the first young very low mass star showing a bipolar molecular outflow in Taurus. The detection boosts the scenario that very low mass objects form like low-mass stars but in a version scaled down by a factor of over 100. © 2011. The American Astronomical Society. All rights reserved..