Near-infrared spectroscopy of embedded protostars in the massive metal-poor star-forming region NGC 346

Abstract

We present medium-resolution (R ∼ 4000) YJ, H & K band spectroscopy of candidate young stellar objects (YSOs) in NGC 346, the most active star-formation region in the metal-poor (Z = 1/5 Z⊙) Small Magellanic Cloud. The spectra were obtained with the KMOS (K-Band Multi Object Spectrograph) integral field instrument on the Very Large Telescope. From our initial sample of 18 candidate high-mass YSOs previously identified from mid-IR photometry and radiative transfer model fits to their spectral energy distributions, approximately half were resolved into multiple components by our integral-field data. In total we detect 30 continuum sources and extract reliable spectra for 12 of these objects. The spectra show various features including hydrogen recombination lines, and lines from H2, He i and [Fe ii], which are indicative of accretion, discs and outflowing material in massive YSOs. We spectroscopically confirm the youthful nature of nine YSO candidates, and identify two others as OB stars. All of the confirmed YSOs have Brγ in emission, but no emission is seen from the CO bandhead, despite other disc tracers present in the spectra. He i 1.083 μm emission is also detected at appreciably higher rates than for the Galaxy.

Young Stellar Objects in NGC 346: A JWST NIRCam/MIRI Imaging Survey

“…In Figure 9, we highlight the locations of these sources with yellow diamonds. We note that of these sources, four are also identified as YSOs by Spitzer surveys of the SMC (Simon et al 2007;Sewiło et al 2013), and two were spectroscopically surveyed in the near-IR with the K-band Multi Object Spectrograph on the Very Large Telescope and shown to be YSOs (Jones et al 2022). Future near-IR spectroscopic studies with JWST of these SED-fitted YSOs and the additional YSO candidates (as determined by NIRCam and MIRI color criteria) will further constrain the nature and properties of these sources.…”

Long-term Evolution of Massive-star Post-common-envelope Circumbinary Disks and the Environments of Fast Luminous Transients

“…observations at other wavelengths (particularly radio; see Section 5.5) may be necessary to distinguish these objects from other IR-bright sources, such as massive protostars (e.g., Jones et al 2022) or other dust-enshrouded supernovae progenitors of a distinct origin (e.g., SN 2008S or the NGC 300 transient; Thompson et al 2009).…”