The Intermediate-mass Young Stellar Object 08576nr292: Discovery of a disk-jet system

TL;DR

This study presents detailed spectroscopic observations of the embedded intermediate-mass young stellar object 08576nr292, revealing a disk-jet system with signs of accretion and outflow, highlighting the capabilities of VLT instruments in studying massive YSOs.

Contribution

First detailed spectroscopic analysis of 08576nr292 showing a disk-jet system around an intermediate-mass YSO, demonstrating the potential of X-shooter and SINFONI for such studies.

Findings

Detection of emission lines indicating accretion and outflow.

Identification of a jet via [Fe II] emission.

Evidence of a circumstellar disk from line profiles.

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 H alpha 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 blue-shifted absorption component at ~ -125 km/s. 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 blue-shifted emission component centered at -125 km/s, coinciding with the absorption components in H alpha 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 Mdot_acc ~ 10^-5 - 10^-6 Msun/yr. 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.