V645Cygni: A decelerating molecular outflow?

Abstract

V 645 Cygni (AFGL 2789) is a young stellar object associated with a bipolar molecular outflow with a modest degree of collimation. In this paper we present IR AM 30-m observations of the CO(J=2→1), CO(J=1→0) and C0(J= 1→0) rotational transition lines toward this region. At relatively low velocities the molecular outflow presents a bipolarity in the north-south direction, with the red and blueshifted CO lobes separated by ∼ 20Prime;. This angular separation decreases as the velocity increases. At higher velocities the outflow appears isotropic. The physical parameters obtained for the V645 Cyg molecular outflow (i.e., mass, momentum rate and mechanical luminosity) are much lower than the parameters derived for other outflows with exciting sources of similar luminosities (L∗≃10 L). In particular, this result makes it possible that radiation pressure may be responsible for generating the stellar wind associated with V645 Cyg. All these results lead us to suggest that the outflowing molecular gas could be decelerating as it moves away from the central V645 Cyg position. The integrated CO emission presents an elongated structure with a velocity gradient of ∼0.7 km s pc in the east-west direction. The mass derived is sufficient to bind these motions.Peer Reviewe