Boogert, A. C. A. and Hogerheijde, M. R. and Ceccarelli, C. and Tielens, A. G. G. M. and van Dishoeck, E. F. and Blake, G. A. and Latter, W. B. and Motte, F. (2002) The Environment and Nature of the Class I Protostar Elias 29: Molecular Gas Observations and the Location of Ices. Astrophysical Journal, 570 (2). pp. 708-723. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20120918-114034201
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A (sub-)millimeter line and continuum study of the Class I protostar Elias 29 in the ρ Ophiuchi molecular cloud is presented whose goals are to understand the nature of this source and to locate the ices that are abundantly present along this line of sight. Within 15"-60" beams, several different components contribute to the line emission. Two different foreground clouds are detected, an envelope/disk system and a dense ridge of HCO^+-rich material. The latter two components are spatially separated in millimeter interferometer maps. We analyze the envelope/disk system by using inside-out collapse and flared disk models. The disk is in a relatively face-on orientation (<60°), which explains many of the remarkable observational features of Elias 29, such as its flat spectral energy distribution, its brightness in the near-infrared, the extended components found in speckle interferometry observations, and its high-velocity molecular outflow. It cannot account for the ices seen along the line of sight, however. A small fraction of the ices is present in a (remnant) envelope of mass 0.12-0.33 M_☉, but most of the ices (~70%) are present in cool (T < 40 K) quiescent foreground clouds. This explains the observed absence of thermally processed ices (crystallized H_2O) toward Elias 29. Nevertheless, the temperatures could be sufficiently high to account for the low abundance of apolar (CO, N_2, O_2) ices. This work shows that it is crucial to obtain spectrally and spatially resolved information from single-dish and interferometric molecular gas observations in order to determine the nature of protostars and to interpret Infrared Space Observatory and future Space Infrared Telescope Facility observations of ices and silicates along a pencil beam.
|Additional Information:||© 2002 American Astronomical Society. Received 2001 September 26; accepted 2002 January 16. We thank Remo Tilanus, Goeran Sandell, and Fred Baas for carrying out part of the JCMT observations in service mode. The research of F. M. and A. C. A. B. at the Caltech Submillimeter Observatory is funded by the NSF through contract AST 99-80846. The research of M. R. H. is supported by the Miller Institute for Basic Research in Science.|
|Subject Keywords:||dust, extinction; infrared: ISM; ISM: molecules; stars: formation; stars: individual (Elias 29); submillimeter|
|Official Citation:||The Environment and Nature of the Class I Protostar Elias 29: Molecular Gas Observations and the Location of Ices A. C. A. Boogert et al. 2002 ApJ 570 708|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||18 Sep 2012 20:03|
|Last Modified:||26 Dec 2012 16:12|
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