The CO Molecular Outflows of IRAS 16293–2422 Probed by the Submillimeter Array

We have mapped the protobinary source IRAS 16293–2422 in CO 2-1,¹³CO 2-1, and CO 3-2 with the Submillimeter Array (SMA). The maps with resolution of 1.5''-5'' reveal a single small-scale (~3000 AU) bipolar molecular outflow along the east-west direction. We found that the blueshifted emission of this small-scale outflow mainly extends to the east and the redshifted emission to the west from the position of IRAS 16293A. A comparison with the morphology of the large-scale outflows previously observed by single-dish telescopes at millimeter wavelengths suggests that the small-scale outflow may be the inner part of the large-scale (~15,000 AU) east-west outflow. On the other hand, there is no clear counterpart of the large-scale northeast-southwest outflow in our SMA maps. Comparing analytical models to the data suggests that the morphology and kinematics of the small-scale outflow can be explained by a wide-angle wind with an inclination angle of ~30°-40° with respect to the plane of the sky. The high-resolution CO maps show that there are two compact, bright spots in the blueshifted velocity range. An LVG analysis shows that the one located 1'' to the east of source A is extremely dense, n(H₂) ~10⁷ cm⁻³, and warm, T_kin > 55 K. The other one located 1^'' southeast of source B has a higher temperature of T_kin > 65 K but slightly lower density of n(H₂) ~10⁶ cm⁻³. It is likely that these bright spots are associated with the hot core-like emission observed toward IRAS 16293. Since both bright spots are blueshifted from the systemic velocity and are offset from the protostellar positions, they are likely formed by shocks.