McMullin, Joseph P. and Mundy, Lee G. and Blake, Geoffrey A. (1993) Structure and chemistry of Orion S. Astrophysical Journal, 405 (2). pp. 599-607. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20120919-141205439
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We present interferometric observations of the SiO J = 2-1, H^(13)CO^+ J = 1-0, HC_3N J = 11-10, CH_3OH J_K = 2_0-1_0, and SO_2 J(K_pK_0) = 8_(17)-8_(08) transitions along with the λ = 3.1 mm continuum toward the young stellar object Orion S. The HC_3N and H^(13)CO^+ emission trace similar spatial and velocity distributions which are extended and follow the Orion molecular ridge. The SiO emission is more spatially confined, peaking to the west of the λ = 3.1 mm continuum source, while the CH_3OH emission peaks to the southwest. Weak SO_2 emission was detected southeast of the continuum source position. Column densities and fractional abundances are derived for each species at different positions in the region. In general, the molecular abundances near the continuum source are similar to those in the quiescent material near IRc 2, but the abundances decrease toward the continuum source position indicating localized depletions of at least a factor of three. The presence of strong SiO emission with much weaker SO_2 emission is interpreted as resulting from high-velocity shock interactions between the outflow from Orion S and the surrounding cloud. The apparent molecular depletions directly toward Orion S, and the similarity of abundances between the Orion S region and quiescent ridge material, suggest that Orion S is at an early stage of chemical evolution, prior to when substantial chemical differentiation occurs.
|Additional Information:||© 1993 American Astronomical Society. Provided by the NASA Astrophysics Data System. Received 1992 June 1; accepted 1992 September 16. We would like to thank the BIMA staff for their help with the observations. We are also very grateful to the developers of the MIRAD software package, and in particular Jim Morgan & Peter Teuben for their guidance and patient attention. This work was sponsored by National Science Foundation, grant AST 9100306 and NASA grant NAGW 3066. G. A. B. gratefully acknowledges support from the David and Lucille Packard and Alfred P. Sloan Foundations, along with NASA grant NAGW-2297. Our special thanks to Lucy Ziurys and Ewine van Dishoeck for critical comments and to Mark McCaughrean for discussions of his infrared images.|
|Subject Keywords:||ISM: abundances; ISM: individual (Orion Nebula); molecular processes-radio lines: ISM|
|Official Citation:||Structure and chemistry of Orion S McMullin, Joseph P.; Mundy, Lee G.; Blake, Geoffrey A Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 405, no. 2, p. 599-607 2003|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||19 Sep 2012 21:58|
|Last Modified:||26 Dec 2012 16:13|
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