Molecular Jets from an Evolved Protostar: Insights from JWST-ALMA Synergy

The combination of the Atacama Large Millimeter/submillimeter Array (ALMA) and JWST/MIRI mid-infrared observations offers a transformative view of protostellar jets and outflows by probing cold and warm gas components across diverse physical conditions. We present a detailed comparison of gas distribution in these regimes for the jet/outflow system associated with G205.46−14.56S3 (HOPS 315), focusing on the inner ∼800 au along the jet. ALMA CO and SiO trace both lobes of the bipolar jet, revealing high-velocity collimated jets and wider outflow components. JWST/MIRI detects mainly the blueshifted lobe; the redshifted side is likely obscured by strong mid-infrared extinction. Shorter-wavelength MIRI H 2 rotational lines (S(7)–S(4)) trace compact jet structures resembling SiO emission, while longer-wavelength lines (S(3)–S(1)) reveal more extended emission akin to low-velocity CO. From H 2 rotational emission, we identify two molecular gas temperature components: warm (∼773 ± 44 K) and hot (∼2499 ± 721 K). Using the ortho-to-para ratio, we estimate visual extinction A V ≈ 23.3 ± 2.5 mag. JWST/MIRI emission implies a jet mass-loss rate of M ̇ J , blue , jwst ≈ ( 0.27 ± 0.1 ) × 1 0 − 6 M ⊙ yr − 1 . The combination of ALMA and JWST reveals stratified layers within the outflow and jet, as well as shock structures, providing a comprehensive view of their physical conditions. This multiwavelength study demonstrates that combining submillimeter observations from ALMA with infrared data from JWST is crucial for uncovering the full physical and chemical structure of protostellar jets and outflows.