In this work, we present spectra of 11 young stellar objects (YSOs) taken with the Mid-Infrared Instrument / Medium Resolution Spectroscopy (MRS) instrument on board the James Webb Space Telescope (JWST). The YSOs are located in the N79 region of the Large Magellanic Cloud (LMC), an active star-forming region with hundreds of Spitzer- and Herschel-identified YSOs and host to super star cluster (SSC) candidate H72.97-69.39. The three giant molecular clouds in N79 (East, West, and South) have varying star formation rates and stellar populations. MRS follow-up observations of four Spitzer-identified YSOs in N79 East, West, and South have revealed that what seemed to be a single, massive YSO is actually a cluster of YSOs. We discuss the emission and absorption lines of six YSOs that have complete or almost-complete spectral coverage from 4.9–27.9 μm. YSO Y3, located in N79 East, is the youngest source in this study and likely to be less than 10,000 yr old, as inferred from the prominent CH4, NH3, CH3OH, CH3OCHO, and CO2 ice absorption features. The most luminous source is the central ionizing YSO of SSC H72.97-69.39, Y4, which has dozens of fine-structure and H2 emission lines. Unlike the other YSOs in this work, Y4 has no polyaromatic hydrocarbon emission lines, due to the intense ionizing radiation destroying these large carbon-chain molecules. The mass accretion rates based on the H i (7-6) line luminosities of YSOs Y1, Y2, Y4, and Y9 range between 1.22 × 10−4–1.89 × 10−2M⊙ yr−1. For the first time in the mid-infrared, we are able to resolve individual high-mass protostars forming in small clusters in an extragalactic environment like the LMC.
JWST Mid-infrared Spectroscopy Resolves Gas, Dust, and Ice in Young Stellar Objects in the Large Magellanic Cloud
Abstract
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© 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
This research relied on the following resources: NASA's Astrophysics Data System and the SIMBAD and VizieR databases, operated at the Centre de Données Astronomiques de Strasbourg, France. This research also made use of Astropy (http://www.astropy.org), a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018, 2022). This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The JWST data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute. The specific observations analyzed can be accessed via doi:10.17909/3rz0-0e55. These observations are associated with program #1235.
O.N. was supported by the Director's Discretionary Fund at the Space Telescope Science Institute and the NASA Postdoctoral Program at NASA Goddard Space Flight Center, administered by Oak Ridge Associated Universities under contract with NASA. M.M. and N.H. acknowledge that a portion of their research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). A.S.H. is supported in part by an STScI Postdoctoral Fellowship. L.L. acknowledges support from the NSF through grant 2054178. O.C.J. acknowledges support from an STFC Webb fellowship. C.N. acknowledges the support of an STFC studentship. P.J.K. acknowledges support from the Science Foundation Ireland/Irish Research Council Pathway program under grant No. 21/PATH-S/9360.
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Additional details
- ISSN
- 1538-4357
- Space Telescope Science Institute
- Director's Discretionary Fund
- National Aeronautics and Space Administration
- NASA Postdoctoral Fellowship
- National Aeronautics and Space Administration
- 80NM0018D0004
- National Science Foundation
- AST-2054178
- Science and Technology Facilities Council
- Science Foundation Ireland
- Irish Research Council
- 21/PATH-S/9360
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)