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Astron. Astrophys. 317, L5-L8 (1997)


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Letter to the Editor

Spectroscopic evidence of mass infall towards
an embedded infrared source in the globule DC 303.8-14.2

K. Lehtinen

Observatory, University of Helsinki, Tähtitorninmäki, P.O. Box 14, FIN-00014 Helsinki, Finland

Received 12 July 1996 / Accepted 20 August 1996

Abstract

We present millimeter molecular line observations towards the embedded infrared source IRAS 13036-7644, located in the globule DC 303.8-14.2. The CS( J =2-1) lines show asymmetrical profiles characteristic of a cloud undergoing gravitational collapse, i.e. double-peaked profiles with a brighter blue-shifted component. In contrast the HCO [FORMULA] ( J =1-0) line shows towards the IRAS source a double-peaked profile with a brighter red-shifted component, and a velocity gradient across the cloud. The hyperfine components of HCN( J =1-0) transition show both kinds of double-peaked profiles, and a velocity gradient. We interpret these results as a simultaneous infall of the dense gas in the core and a non-collapsing envelope.

The IRAS source drives a bipolar molecular outflow detected in the 12 CO( J =1-0) transition.

Key words: Line: profiles — Stars: formation — ISM: clouds — ISM: individual objects: DC 303.8-14.2 — ISM: individual objects: IRAS 13036-7644 — ISM: jets and outflows


© European Southern Observatory (ESO) 1997

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