Chemical Change in the Disk Forming Region of IRAS 16293–2422 Studied with ALMA

Abstract

AbstractWe have analyzed rotational spectral line emission of OCS, CH3OH, HCOOCH3, and H2CS observed toward the low-mass Class 0 protostar IRAS 16293–2422 (Source A and B) at a sub-arcsecond resolution with ALMA. Significant chemical differentiation is found at a 50 au scale. OCS is found to trace the infalling-rotating envelope, while COM distributions are concentrated around the inner part of the envelope. The kinematic structure in Source A is explained with a ballistic model, and the protostellar mass and the radius of the centrifugal barrier are evaluated to be ~0.75 M⊙ and ~50 au, respectively. This study has revealed that the centrifugal barrier plays a central role not only in the disk formation but also in the associated chemical evolution.