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. TheHe 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 ∼ 10−6–10−5M 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.