Volume 534, October 2011
|Number of page(s)||28|
|Section||Interstellar and circumstellar matter|
|Published online||13 October 2011|
Arcsecond resolution images of the chemical structure of the low-mass protostar IRAS 16293-2422
An overview of a large molecular line survey from the Submillimeter Array⋆
Centre for Star and Planet Formation, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø., Denmark
2 Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K., Denmark
3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street MS42, Cambridge, MA 02138, USA
4 Laboratoire AIM, CEA/DSM, IRFU/Service d’Astrophysique, 91191 Gif-sur-Yvette Cedex, France
5 Argelander Institute for Astronomy, University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
6 Academia Sinica Institute of Astronomy and Astrophysics, PO Box 23-141, Taipei 10617, Taiwan
Received: 26 April 2011
Accepted: 30 August 2011
It remains a key challenge to establish the molecular content of different components of low-mass protostars, like their envelopes and disks, and how this depends on the evolutionary stage and/or environment of the young stars. Observations at submillimeter wavelengths provide a direct possibility to study the chemical composition of low-mass protostars through transitions probing temperatures up to a few hundred K in the gas surrounding these sources. This paper presents a large molecular line survey of the deeply embedded protostellar binary IRAS 16293-2422 from the Submillimeter Array (SMA) – including images of individual lines down to ≈1.5−3″ (190−380 AU) resolution. More than 500 individual transitions are identified related to 54 molecular species (including isotopologues) probing temperatures up to about 550 K. Strong chemical differences are found between the two components in the protostellar system with a separation between, in particular, the sulfur- and nitrogen-bearing species and oxygen-bearing complex organics. The action of protostellar outflow on the ambient envelope material is seen in images of CO and SiO and appear to influence a number of other species, including (deuterated) water, HDO. The effects of cold gas-phase chemistry is directly imaged through maps of CO, N2D+ and DCO+, showing enhancements of first DCO+ and subsequently N2D+ in the outer envelope where CO freezes-out on dust grains.
Key words: circumstellar matter / ISM: molecules / stars: formation / ISM: jets and outflows / submillimeter: ISM / ISM: individual objects: IRAS 16293-2422
Appendix A is available in electronic form at http://www.aanda.org
© ESO, 2011
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