Oral Presentation

A 10 au Scale View of the Low-Mass Protostellar Source IRAS 16293-2422 Source A

Author(s): Yoko Oya, and Satoshi Yamamoto (The University of Tokyo, Japan)

Presenter: Yoko Oya (The University of Tokyo)

IRAS 16293-2422 is a low-mass Class 0 protostellar binary located in Ophiuchus (d = 140 pc). As for one component of this binary system (Source A), we have reported that the transition from the infalling envelope to the rotating disk is occurring with a radius of 50 au. Recently, we have observed this source in the C17O and H2CS lines with ALMA (Cycle 4) at an angular resolution of 0".1 (14 au). The 1.3 mm dust continuum emission reveals the sub-structures within 100 au in radius. The C17O line traces the envelope gas on a 300 au scale, while it is not seen within 50 au. We have derived the rotation temperature of H2CS on a 10 au scale. As approaching to one of the 1.3 mm continuum peak (A1), the rotation temperature steeply rises as high as >300 K at the radius of 50 au from A1. It is likely due to a local accretion shock and/or the thermal heating in the transition zone from the envelope to the disk. This position corresponds where the organic molecular lines are enhanced. The rise of the rotation temperature would be related to the peculiar chemical characteristics of this famous hot corino source.