Oral Presentation
Probing the Earliest Stage of Protostellar Evolution
Presenter: Naomi Hirano (ASIAA (Former Research Fellow))
We have observed the low-mass molecular cloud core G204.4-11.3A2-NE (G204NE) in the Orion B giant molecular cloud with the Atacama Large Millimeter/submillimeter Array in Band 6. The 1.3 mm continuum images and visibilities unveil a compact central structure with a radius of ~12 au, while showing no signature of binarity down to 18 au. The bolometric temperature and luminosity of this source are derived to be ~33 K and ~1.1 L_sun, respectively. Chemical stratification is observed in dense gas tracers, with C18O emission peaking at the continuum position surrounded by the spatially extended emission of N2D+ and DCO+. This implies that the core is in a very early evolutionary stage in which CO depletion occurs in most regions except for a small area heated by the central source. The envelope kinematics indicates a rotating and infalling structure with a central protostar mass of 0.07 M_sun. The protostar drives a collimated outflow traced by CO, SiO, SO, and H2CO, with misaligned blueshifted and redshifted lobes exhibiting a pair of bow-like patterns. High-velocity jets, extending up to 720 au, are detected in CO, SiO, and SO lines. The jet launching region is likely at the outer edge of the dust sublimation zone. The absence of a binary signature suggests the outflows and jets are driven by a single protostar, although a close binary cannot be ruled out. The observed deflection of the outflows and jet is likely due to turbulent accretion in a moderately magnetized core
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