2005/12/08 by Anthony J. Remijan, J. M. Hollis · 2 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/500239
published as Astrophys.J.640:842-848,2006 · 18 pages, 5 figures, accepted for publication in the Astrophysical Journal
arxiv created 2005/12/08 · openalex publication_date 2006/03/27 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We report high spatial resolution VLA observations of the low-mass star-forming region IRAS 16293-2422 using four molecular probes: ethyl cyanide (CH 3 CH 2 CN), methyl formate (CH 3 OCHO), formic acid (HCOOH), and the ground vibrational state of silicon monoxide (SiO). Ethyl cyanide emission has a spatial scale of ~20'' and encompasses binary cores A and B as determined by continuum emission peaks. Surrounded by formic acid emission, methyl formate emission has a spatial scale of ~6'' and is confined to core B. SiO emission shows two velocity components with spatial scales less than 2'' that map ~2'' northeast of the A and B symmetry axis. The redshifted SiO is ~2'' northwest of blueshifted SiO along a position angle of ~135° which is approximately parallel to the A and B symmetry axis. We interpret the spatial position offset in red- and blueshifted SiO emission as due to rotation of a protostellar accretion disk, and we derive ~1.4 M ☉ interior to the SiO emission. In the same vicinity, Mundy et al. also concluded rotation of a nearly edge-on disk from OVRO observations of much stronger and ubiquitous 13 CO emission, but the direction of rotation is opposite to the SiO emission findings. Taken together, SiO and 13 CO data suggest evidence for a counterrotating disk. Moreover, archival BIMA array 12 CO data show an inverse P Cygni profile with the strongest absorption in close proximity to the SiO emission, indicating unambiguous material infall toward the counterrotating protostellar disk at a new source location within the IRAS 16293-2422 complex. The details of these observations and our interpretations are discussed.