The Stellar Population of NGC 346 in the Small Magellanic Cloud with JWST

Vollständiger Abstract

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Abstract NGC 346 is a massive star-forming region located at a distance of ∼62 kpc, in the Small Magellanic Cloud. Due to its low metallicity ( Z ∼ 1/5 Z ⊙ ), it is an ideal environment to study star formation and stellar population analogs to those at Cosmic Noon. In this work, we produce a combined JWST NIRCam and MIRI photometric catalog of NGC 346. We characterise different stellar populations in the region: the upper main sequence (UMS), red giant branch (RGB), and red clump (RC), as well as pre-main-sequence (pre-MS) stars and young stellar objects (YSOs). We performed point-spread function-weighted photometry in 11 wavelength bands across NIRCam and MIRI and utilized multiple color–magnitude diagrams to identify the various stellar populations in the field. Our final photometric catalog of NGC 346 comprises 249,519 unique sources, including 2024 UMS stars, 2755 RGB stars, and 742 RC stars. In addition, we identified 6274 candidate pre-MS stars, 7350 candidate YSOs, and 23,819 IR-excess sources. Combining these three categories, we characterised 1583 strong and 3761 likely pre-MS/YSO candidates. By utilizing the F115W − F200W versus F115W − F187N color–color diagram, we found 239 nonspurious sources with Pa α excess, indicating accretion and star formation in NGC 346. Using JWST NIRCam and MIRI observations, we produced the deepest catalog to date of the star formation region NGC 346 in the near- and mid-IR range (1–21 μ m). Our catalog and characterisations of the young and old populations will provide the basis for detailed follow-up studies.