Previous   |   Session 81   |   Next  |   Author Index   |   Block Schedule

[81.28] IRAS 16293-2422: Evidence for Infall onto a Counter-Rotating Protostellar Accretion Disk

A. J. Remijan, J. M. Hollis (NASA's GSFC)

We report high spatial resolution VLA observations of the low-mass star-forming region IRAS 16293-2422 using four molecular probes: ethyl cyanide (CH₃CH₂CN), methyl formate (CH₃OCHO), 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^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 ~1.4 Solar Masses 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 ¹³CO emission but the direction of rotation is opposite to the SiO emission findings. Taken together, SiO and ¹³CO data suggest evidence for a counter-rotating disk. Moreover, archival BIMA array ¹²CO 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.

Previous   |   Session 81   |   Next

Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.