Dissection of the protostellar envelope surrounding IRAS 05173-0555 in L1634

¹ Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Martí i Franquès 1, 08028, Barcelona, Catalunya, Spain e-mail: mbeltran@am.ub.es
² NASA-Goddard Space Flight Center, Greenbelt, MD 20771, USA
³ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
⁴ Academia Sinica, Institute of Astronomy and Astrophysics, PO Box 23–141, Taipei 106, Taiwan
⁵ Jodrell Bank Centre for Astrophysics, Alan Turing Building, University of Manchester, Manchester, M13 9PL, UK
⁶ National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA

Received: 10 December 2007
Accepted: 25 March 2008

Abstract

Context. The youngest protostars that power energetic outflows are surrounded by infalling and rotating envelopes that contain most of the mass of the system.

Aims. We study the properties and kinematics of the protostellar envelope surrounding the embedded source IRAS 05173-0555  in L1634.

Methods. We carried out VLA ammonia observations at 1.3 cm with the VLA in the D configuration to map the gas towards the core of L1634.

Results. The NH₃ emission towards IRAS 05173-0555 is resolved and shows two components that are clearly distinguishable morphologically: a cross-like structure, roughly elongated in the direction of the HH 240/241 outflow and associated with IRAS 05173-0555, plus an arc-like stream elongated towards the north. The properties and kinematics of the gas suggest that the origin of the cross-like morphology could be the interaction between the outflow and the envelope. A more compact and flattened structure, which could be undergoing rotation about the axis of the outflow, has been detected towards the center of the cross-like envelope. The northern stream, which has properties and velocity that are different from those of the cross-like envelope, is likely part of the original cloud envelope, and could be a quiescent core that may never form stars, or instead be in a prestellar phase.