James Webb Space Telescope Feed Post

Arxiv: Unveiling two deeply embedded young protostars in the S68N Class 0 protostellar core with JWST/NIRSpec Published: 10/15/2024 12:16:10 AM Updated: 10/15/2024 12:16:10 AM

Paper abstract: The near-infrared (NIR) emission of the youngest protostars still needs to becharacterized to better understand the evolution of their accretion andejection activity. We analyze James Webb Space Telescope NIRSpec 1.7 -- 5.3\mum observations of two deeply embedded sources in the S68N protostellarcore in Serpens. The North Central (NC) source exhibits a highly obscuredspectrum (A_K ~ 4.8 mag) that is modeled with a pre-main-sequence photosphereand a hot disk component. The photospheric parameters are consistent with ayoung, low-mass photosphere, as suggested by the low surface gravity, log g of1.94 \pm 0.15 cm s^{-2}. The hot disk suggests that accretion onto thecentral protostellar embryo is ongoing, although prototypical accretion-tracingemission lines HI are not detected. The South Central (SC) source, which iseven more embedded (A_K ~ 8 mag; no continuum is detected shortward of 3.6\mum) appears to be driving the large-scale S68N protostellar outflow, andlaunches a collimated hot molecular jet detected in \Ht and CO ro-vibrationallines. Shock modeling of the \Ht (ro)vibrational lines establishes that fastC-type shocks (>= 30 km s^{-1}), with high pre-shock density (>=10^7 cm^{-3}), and strong magnetic field (b ~ 3--10, where B =b\,\times\,\sqrt{\textrm{n}_{\textrm{H}} (\textrm{cm}^{-3})}\,\mu\textrm{G})best match the data. The bright CO fundamental line forest suggests energeticexcitation, with the contribution of non-LTE effects, ie irradiation pumping.Detected OH and CH^{+} ro-vibrational lines support this hypothesis. Thesetwo Class 0 protostars seem to be in very young evolutionary stages and stillhave to acquire the bulk of their final stellar masses. These resultsdemonstrate that JWST enables unprecedented diagnostics of these first stagesof the protostellar evolutionary phase.