Subarcsecond Analysis of Infalling-Rotating Envelope around the Class I
  Protostar IRAS 04365+2535
  Sub-arcsecond images of the rotational line emission of CS and SO have been
obtained toward the Class I protostar IRAS 04365$+$2535 in TMC-1A with ALMA. A
compact component around the protostar is clearly detected in the CS and SO
emission. The velocity structure of the compact component of CS reveals
infalling-rotating motion conserving the angular momentum. It is well explained
by a ballistic model of an infalling-rotating envelope with the radius of the
centrifugal barrier (a half of the centrifugal radius) of 50 AU, although the
distribution of the infalling gas is asymmetric around the protostar. The
distribution of SO is mostly concentrated around the radius of the centrifugal
barrier of the simple model. Thus a drastic change in chemical composition of
the gas infalling onto the protostar is found to occur at a 50 AU scale
probably due to accretion shocks, demonstrating that the infalling material is
significantly processed before being delivered into the disk.
