2025/03/18 by Cheng, Yu, Tan, Jonathan C., Andersen, Morten +5
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2503.14460
Star formation is a fundamental, yet poorly understood, process of the Universe. It is important to study how star formation occurs in different galactic environments. Thus, here, in the first of a series of papers, we introduce the Low-Metallicity Star Formation (LZ-STAR) survey of the Sh2-284 (hereafter S284) region, which, at Z∼ 0.3-0.5Z_\odot, is one of the lowest-metallicity star-forming regions of our Galaxy. LZ-STAR is a multi-facility survey, including observations with \it JWST, \it ALMA, \it HST, \it Chandra and \it Gemini. As a starting point, we report \it JWST and \it ALMA observations of one of the most massive protostars in the region, S284p1. The observations of shock-excited molecular hydrogen reveal a symmetric, bipolar outflow originating from the protostar, spanning several parsecs, and fully covered by the \it JWST field of view and the \it ALMA observations of CO(2-1) emission. This allows us to infer that the protostar has maintained a relatively stable orientation of disk accretion over its formation history. The \it JWST near-IR continuum observations detect a centrally illuminated bipolar outflow cavity around the protostar, as well as a surrounding cluster of low-mass young stars. We develop new radiative transfer models of massive protostars designed for the low metallicity of S284. Fitting these models to the protostar's spectral energy distribution implies a current protostellar mass of ∼10 M_\odot has formed from an initially ∼100 M_\odot core over the last ∼3×105 years. Overall, these results indicate that massive stars can form in an ordered manner in low-metallicity, protocluster environments.