IRAS 16293-2422: proper motions, jet precession, the hot core, and the   unambiguous detection of infall
  We present observations of IRAS 16293-2422 using the Submillimeter Array (SMA) at 300 GHz, and the Very Large Array (VLA) at frequencies from 1.5 to 43 GHz. This source was already known to be a binary system with components A and B separated by ~5". The new SMA data now separate source A into two submm continuum components, denoted Aa and Ab. The strongest of these, Aa, peaks between the cm radio sources A1 and A2. Archival VLA data show proper motion of sources A and B of 17 mas/yr, associated with motion of the rho Ophiuchi cloud. We also find relative motion between A1 and A2 which excludes the possibility that they are gravitationally bound. A2 remains stationary relative to source B, and we identify it as the protostar driving the NE-SW CO outflow. A1 is shock-ionized gas where a precessing jet interacts with dense gas. This jet probably drives the E-W CO outflow. The origin of this jet must be located close to A2, and may be the submm source Aa. Thus source A is now shown to comprise three components within 1". Source B, however, is single, exhibits optically-thick dust emission even at 8 GHz, has a high luminosity, and yet shows no sign of outflow, indicating it is probably very young.   The SMA spectrum of IRAS 16293-2422 reports the first astronomical identification of many lines at 300 and 310 GHz. The species detected are typical of hot cores, and are mainly associated with source A. We suggest the shock at A1 may explain the enhanced abundances measured, especially of sulphur-bearing molecules. We use the high brightness temperature of the submm dust emission from source B to demonstrate the unambiguous detection of infall by observing redshifted SO (7_7-6_6) absorption against the dust disk. 
Claire J. Chandler (1), Crystal L. Brogan (2), Yancy L. Shirley (1),   and Laurent Loinard (3) ((1) NRAO, (2) U. Hawaii, (3)...