THE intermediate-mass young stellar object 08576nr292: Discovery of a disk-jet system

Abstract

We present observations of the embedded massive young stellar object (YSO) candidate 08576nr292, obtained with X-shooter and SINFONI on the ESO Very Large Telescope (VLT). The flux-calibrated, medium-resolution X-shooter spectrum (300-2500 nm) includes over 300 emission lines, but no (photospheric) absorption lines, and is consistent with a reddened disk spectrum. Among the emission lines are three hydrogen series and helium lines, both permitted and forbidden metal lines, and CO first-overtone emission. A representative sample of lines with different morphologies is presented. The Hα and Ca II triplet lines are very strong, with profiles indicative of outflow and - possibly - infall, usually observed in accreting stars. These lines include a blueshifted absorption component at ∼-125 km s-1. The He I and metal-line profiles are double peaked, with a likely origin in a circumstellar disk. The forbidden lines, associated with outflow, have a single blueshifted emission component centered at -125 km s-1, coinciding with the absorption components in Hα and Ca II. SINFONI H- and K-band integral-field spectroscopy of the cluster environment demonstrates that the [Fe II] emission is produced by a jet originating at the location of 08576nr292. Because the spectral type of the central object cannot be determined, its mass remains uncertain. We argue that 08576nr292 is an intermediate-mass YSO with a high accretion rate (Macc ∼ 10-6 -10-5 M ̇ yr-1). These observations demonstrate the potential of X-shooter and SINFONI to study in great detail an accretion disk-jet system, rarely seen around the more massive YSOs. © 2011. The American Astronomical Society. All rights reserved.