Who is eating the outflow? High-angular resolution study of an intermediate-mass protostar in L1206

¹ Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona, Catalunya, Spain e-mail: mbeltran@am.ub.es
² Institut de Ciències de l'Espai (CSIC-IEEC), Campus UAB, Facultat de Ciències, Torre C-5, 08193, Bellaterra, Catalunya, Spain

Received: 3 March 2006
Accepted: 3 April 2006

Abstract

Context.Up to now only a few intermediate-mass molecular outflows have been studied with enough high-angular resolution.

Aims.The aim of this work is to study in detail the intermediate-mass YSO IRAS 22272+6358A, which is embedded in L1206, and its molecular outflow, to investigate the interaction of the outflow with the dense protostellar material and to compare their properties with those of lower mass counterparts.

Methods.We carried out OVRO observations of the 2.7 mm continuum emission, CO (), C¹⁸O(), and HC₃N () to map the core of L1206 with high-angular resolution and to derive the properties of the dust emission, the molecular outflow, and the dense protostellar envelope.

Results.The 2.7 mm continuum emission has been resolved into four sources, labeled OVRO 1, 2, 3, and 4. The intermediate-mass Class 0/I object OVRO 2, with a mass traced by the dust emission of 14.2 , is the source associated with IRAS 22272+6358A. The CO () observations have revealed a very collimated outflow driven by OVRO 2, at a PA , that has a very weak southeastern red lobe and a much stronger northwestern blue lobe. Photodissociation toward the red lobe produced by the ionization front coming from the bright-rimmed diffuse Hii region could be responsible for the morphology of the outflow. The spatial correlation between the outflow and the elongated dense protostellar material traced by HC₃N () suggests an interaction between the molecular outflow and the protostellar envelope. Shocks produced by the molecular outflow, and possibly by the shock front preceding the ionization front, could account for the southern enhancement of HC₃N. The properties of the intermediate-mass protostar OVRO 2 and the molecular outflow are consistent with those of lower mass counterparts. The C¹⁸O abundance relative to molecular hydrogen estimated toward OVRO 2 is , a value ~6 to 13 times lower than typical abundances estimated toward molecular clouds. The most plausible explanation for such a difference is CO depletion toward OVRO 2.