IRAS 16293−2422: Evidence for Infall onto a Counterrotating Protostellar Accretion Disk
Open Access
- 1 April 2006
- journal article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 640 (2), 842-848
- https://doi.org/10.1086/500239
Abstract
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 emiss ion has a spatial scale of $sim20''$ 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 $sim6''$and is confined to core B. SiO emission shows two velocity components with spatial scales less than 2$''$ that map $sim2''$ northeast of the A and B symmetry axis. The redshifted SiO is $sim2''$ northwest of blueshifted SiO along a position angle of $sim135^o$ 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 $sim$1.4 M$_{odot}$ interior to the SiO emission. In the same vicinity, Mundy et al. (1986) 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 counter-rotating 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 counter-rotating protostellar disk at a new source location within the IRAS 16293-2422 complex. The details of these observations and our interpretations are discussed.Comment: 18 pages, 5 figures, accepted for publication in the Astrophysical Journa
Keywords
This publication has 19 references indexed in Scilit:
- IRAS 16293−2422: Proper Motions, Jet Precession, the Hot Core, and the Unambiguous Detection of InfallThe Astrophysical Journal, 2005
- Near-Arcsecond Resolution Observations of the Hot Corino of the Solar-Type Protostar IRAS 16293-2422The Astrophysical Journal, 2004
- Organic Molecules in Low-Mass Protostellar Hot Cores: Submillimeter Imaging of IRAS 16293-2422The Astrophysical Journal, 2004
- Green Bank Telescope Observations of Interstellar Glycolaldehyde: Low-Temperature SugarThe Astrophysical Journal, 2004
- Green Bank Telescope Detection of New Interstellar Aldehydes: Propenal and PropanalThe Astrophysical Journal, 2004
- The Hot Core around the Low-Mass Protostar IRAS 16293-2422: Scoundrels Rule!The Astrophysical Journal, 2003
- A Sensitive Very Large Array Search for Small‐Scale Glycine Emission toward OMC‐1The Astrophysical Journal, 2003
- Formic Acid in Orion KL from 1 Millimeter Observations with the Berkeley‐Illinois‐Maryland Association ArrayThe Astrophysical Journal, 2002
- Unveiling the Circumstellar Envelope and Disk: A Subarcsecond Survey of Circumstellar StructuresThe Astrophysical Journal, 2000
- Molecular abundances and low-mass star formation. 1: Si- and S-bearing species toward IRAS 16293-2422The Astrophysical Journal, 1994