Detection of Interstellar Ortho-D2H+ with SOFIA

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http://hdl.handle.net/10138/214439

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Harju , J , Sipilä , O , Brunken , S , Schlemmer , S , Caselli , P , Juvela , M , Menten , K M , Stutzki , J , Asvany , O , Kaminski , T , Okada , Y & Higgins , R 2017 , ' Detection of Interstellar Ortho-D2H+ with SOFIA ' , Astrophysical Journal , vol. 840 , no. 2 , 63 . https://doi.org/10.3847/1538-4357/aa6c69

Title: Detection of Interstellar Ortho-D2H+ with SOFIA
Author: Harju, Jorma; Sipilä, Olli; Brunken, Sandra; Schlemmer, Stephan; Caselli, Paola; Juvela, Mika; Menten, Karl M.; Stutzki, Juergen; Asvany, Oskar; Kaminski, Tomasz; Okada, Yoko; Higgins, Ronan
Contributor: University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
Date: 2017-05-10
Language: eng
Number of pages: 13
Belongs to series: Astrophysical Journal
ISSN: 0004-637X
URI: http://hdl.handle.net/10138/214439
Abstract: We report on the detection of the ground-state rotational line of ortho-D2H+ at 1.477 THz (203 mu m) using the German REceiver for Astronomy at Terahertz frequencies (GREAT) on. board the Stratospheric Observatory For Infrared Astronomy (SOFIA). The line is seen in absorption against. far-infrared continuum from the protostellar binary IRAS 16293-2422 in Ophiuchus. The para-D2H+ line at 691.7 GHz was not detected with the APEX telescope toward this position. These D2H+ observations complement our previous detections of para-H2D+ and ortho-H2D+ using SOFIA and APEX. By modeling chemistry and radiative transfer in the dense core surrounding the protostars, we find that the ortho-D2H+ and para-H2D+ absorption features mainly originate in the cool (T <18 K) outer envelope of the core. In contrast, the ortho-H2D+ emission from the core is significantly absorbed by the ambient molecular cloud. Analyses of the combined D2H+ and H2D+ data result in an age estimate of similar to 5. x. 10(5) yr for the core, with an uncertainty of similar to 2. x. 10(5) yr. The core material has probably been pre-processed for another 5. x. 10(5) years in conditions corresponding to those in the ambient molecular cloud. The inferred timescale is more than 10 times the age of the embedded protobinary. The D2H+ and H2D+ ions have large and nearly equal total (ortho+ para) fractional abundances of similar to 10(-9) in the outer envelope. This confirms the central role of H-3 + in the deuterium chemistry in cool, dense gas, and adds support to the prediction of chemistry models that also D-3(+) should be abundant in these conditions.
Subject: astrochemistry
ISM: individual objects (IRAS 16293-2422)
ISM: molecules
stars: formation
LOW-MASS PROTOSTAR
GOULD BELT SURVEY
TO-PARA RATIO
PRESTELLAR CORES
IRAS 16293-2422
DEUTERIUM FRACTIONATION
RADIATIVE-TRANSFER
DEUTERATED H-3(+)
MOLECULAR CLOUDS
STAR-FORMATION
115 Astronomy, Space science
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