Low-mass stars are the most numerous stellar objects in the Universe. Before the James Webb Space Telescope (JWST), we had limited knowledge of how planetary systems around low-mass stars could form at subsolar metallicities. Here we present JWST observations of NGC 346, a star-forming region in the metal-poor Small Magellanic Cloud, revealing a substantial population of subsolar-mass young stellar objects (YSOs) with an infrared excess. We notice that continuing low-mass star formation is concentrated along dust filaments. We detected roughly 500 YSOs and pre-main-sequence (PMS) stars from more than 45,000 unique sources, using all four NIRCam wide filters with deep, high-resolution imaging. From these observations, we construct detailed near-infrared colour–magnitude diagrams with which preliminary categorizations of YSO classes are made. For the youngest, most deeply embedded objects, JWST/NIRCam is ten magnitudes more sensitive than Spitzer observations at comparable wavelengths, and reaches two magnitudes fainter than Hubble Space Telescope for more evolved PMS sources, corresponding to roughly 0.1 M⊙. The infrared sensitivity and resolution of JWST allows us to detect embedded low-mass star formation in an extragalactic environment. Furthermore, evidence of infrared excesses and accretion suggests that the dust required for rocky planet formation is present at metallicities as low as 0.2 Z⊙, which are akin to those in place at cosmic noon.
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The data used in this study may be obtained from the Mikulski Archive for Space Telescopes (MAST, https://mast.stsci.edu/) and are associated with program no. 1227.
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This work is based on observations made with the NASA/ESA/CSA JWST. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract no. NAS 5-03127 for JWST. These observations are associated with program no. 1227. O.C.J. acknowledges support from a Science and Technology Facilities Council Webb fellowship. K.F. acknowledges support through the ESA Research Fellowship. M.M. acknowledges support through a NASA/JWST grant no. 80NSSC22K0025. M.M., N.H. and L.L. acknowledge support from the National Science Foundation through grant no. 2054178. L.E.U.C. was supported by an appointment to the NASA Postdoctoral Program at the NASA Ames Research Center, administered by Oak Ridge Associated Universities under contract with NASA. O.N. acknowledges support from STScI Director’s Discretionary Fund.
The authors declare no competing interests.
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Jones, O.C., Nally, C., Habel, N. et al. JWST/NIRCam detections of dusty subsolar-mass young stellar objects in the Small Magellanic Cloud. Nat Astron 7, 694–701 (2023). https://doi.org/10.1038/s41550-023-01945-7