Uncovering the hidden physical structures and protostellar activities in the low-metallicity S284-RE region: results from ALMA and JWST

Abstract

We present an observational study of the S284-RE region, a low-metallicity area associated with the extended S284 H ii region. A thermally supercritical filament (mass ∼2402 M⊙ and length ∼8.5 pc) is investigated using the Herschel column density map. The Spitzer ratio 4.5 μm/3.6 μm map traces the H2 outflows in this filament, where previously reported young stellar objects (YSOs) are spatially distributed. Analysis of the YSO distribution has revealed three active star-forming clusters (YCl1, YCl2, and YCl3) within the filament. YCl3 seems to be the most evolved and YCl2 the youngest, while YCl1 displays signs of nonthermal fragmentation. The JWST (F470N+F444W)/F356W ratio map reveals at least seven bipolar H2 outflows, with four (olc1–olc4) in YCl1 and three (ol1–ol3) in YCl2. The driving sources of these outflows are identified based on outflow geometry, Atacama Large Millimeter/submillimeter Array (ALMA) continuum peaks, and YSO positions. Two ALMA continuum sources—#2 and #3—from the M–Reff plot are recognized as potential massive star formation candidates. ALMA continuum source #2 hosts at least three outflow-driving sources, whereas ALMA continuum source #3 contains two. The bipolar outflow olc1, driven by an embedded object within continuum source #2, is likely a massive protostar, as indicated by the Br-α and PAH emissions depicted in the JWST (F405N+F444W)/F356W ratio map. The presence of H2 knots in the outflows olc1 and ol1 suggests episodic accretion. Overall, the study investigates a massive protostar candidate, driving the ∼2.7 pc H2 outflow olc1 and undergoing episodic accretion.