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)\ncandidate 08576nr292, obtained with X-shooter and SINFONI on the ESO Very Large\nTelescope (VLT). The flux-calibrated, medium-resolution X-shooter spectrum (300\n- 2500 nm) includes over 300 emission lines, but no (photospheric) absorption\nlines and is consistent with a reddened disk spectrum. Among the emission lines\nare three hydrogen series and helium lines, both permitted and forbidden metal\nlines, and CO first-overtone emission. A representative sample of lines with\ndifferent morphologies is presented. The H alpha and Ca II triplet lines are\nvery strong, with profiles indicative of outflow and - possibly - infall,\nusually observed in accreting stars. These lines include a blue-shifted\nabsorption component at ~ -125 km/s. The He I and metal-line profiles are\ndouble-peaked, with a likely origin in a circumstellar disk. The forbidden\nlines, associated with outflow, have a single blue-shifted emission component\ncentered at -125 km/s, coinciding with the absorption components in H alpha and\nCa II. SINFONI H- and K-band integral-field spectroscopy of the cluster\nenvironment demonstrates that the [Fe II] emission is produced by a jet\noriginating at the location of 08576nr292. Because the spectral type of the\ncentral object cannot be determined, its mass remains uncertain. We argue that\n08576nr292 is an intermediate-mass YSO with a high accretion rate Mdot_acc ~\n10^-5 - 10^-6 Msun/yr. These observations demonstrate the potential of\nX-shooter and SINFONI to study in great detail an accretion disk-jet system,\nrarely seen around the more massive YSOs.\n