Detection of OH+ and H2O+ towards Orion KL

H. C. Gupta (1) , P. Rimmer (2, 3, 4) , J. C. Pearson (5) , S. Yu (1) , E. Herbst (6, 7) , N. Harada (6, 7, 8) , E. A. Bergin (9) , D. A. Neufeld , G. J. Melnick (10) , R. Bachiller (11) , W. Baechtold (12) , T. A. Bell , G. A. Blake (13) , E. Caux (14, 14) , C. Ceccarelli (11) , J. Cernicharo (15) , G. Chattopadhyay (1) , C. Comito (16) , S. Cabrit (17) , N. R. Crockett , F. Daniel (15, 17, 18) , E. Falgarone (19) , M. C. Diez-Gonzalez , M.-L. Dubernet (17) , N. Erickson , M. Emprechtinger (20) , P. Encrenaz (17) , M. Gerin (17, 19) , J. J. Gill , T. F. Giesen , J. R. Goicoechea (17) , P. F. Goldsmith , C. Joblin (14) , D. Johnstone (21) , W. D. Langer , B. Larsson (11) , W. B. Latter , R. H. Lin , D. C. Lis (22) , R. Liseau (5) , S. D. Lord , F. W. Maiwald (11) , S. Maret (11) , P. G. Martin (23) , J. Martin-Pintado (11) , K. M. Menten (24) , P. Morris (25) , H. S. P. Müller , J. A. Murphy , L. H. Nordh , M. Olberg (26) , V. Ossenkopf (27, 28) , L. Pagani (17) , M. Pérault (17) , T. G. Phillips (22) , R. Plume (29) , S.-L. Qin , M. Salez (11) , L. A. Samoska , P. Schilke (16, 30) , E. Schlecht , S. Schlemmer (30) , R. Szczerba , J. Stutzki (30) , N. Trappe (31) , F. F. S. van Der Tak (32, 28) , C. Vastel (14, 14) , S. Wang (9) , H. W. Yorke , J. Zmuidzinas (20) , A. Boogert (11) , R. Güsten (16) , P. Hartogh (33) , N. Honingh , A. Karpov (34) , J. Kooi , J.-M. Krieg (17) , R. Schieder , P. Zaal

1 JPL - Jet Propulsion Laboratory
2 Ohio State university Departement of Physic, Colombus
3 Ohio State university Departement of Astronomy, Colombus
4 Ohio State university Departement of Chemistry, Colombus
5 FL - foreign laboratories
6 Ohio State Univ, Dept Phys, Columbus, OH 43210 USA
7 Ohio State Univ, Dept Astron & Chem, Columbus, OH 43210 USA
8 Ohio State University Dept Chemistry
9 Department of Astronomy [Ann Arbor]
10 CfA - Harvard-Smithsonian Center for Astrophysics
11 LAOG - Laboratoire d'Astrophysique de Grenoble
12 MWE - Millimeter-Wave Electronics Laboratory [ETH Zürich]
13 LOCIE - LabOratoire proCédés énergIe bâtimEnt
14 CESR - Centre d'étude spatiale des rayonnements
15 CAB - Centro de Astrobiologia [Madrid]
16 Max Planck Institute for Radio Astronomy
17 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
18 ENS-PSL - École normale supérieure - Paris
19 LRA - Laboratoire de Radioastronomie
20 Cahill Center for Astronomy and Astrophysics
21 Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V9E 2E7 Canada
22 CALTECH - California Institute of Technology
23 LM2C - Laboratoire de Modélisation Multi-échelles des Combustibles
24 MPIFR - Max-Planck-Institut für Radioastronomie
25 IPAC - Infrared Processing and Analysis Center
26 Onsala Space Observatory
27 LUTH (UMR_8102) - Laboratoire Univers et Théories
28 SRON - SRON Netherlands Institute for Space Research
29 Department of Physics and Astronomy [Calgary]
30 I. Physikalisches Institut [Köln]
31 LDAR (EA_4434) - Laboratoire de Didactique André Revuz
32 Kapteyn Astronomical Institute [Groningen]
33 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
34 IAP - A.M.Obukhov Institute of Atmospheric Physics

We report observations of the reactive molecular ions OH+, H2O+, and H3O+ towards Orion KL with Herschel/HIFI. All three N = 1-0 fine-structure transitions of OH+ at 909, 971, and 1033 GHz and both fine-structure components of the doublet ortho-H2O+ 111-000 transition at 1115 and 1139 GHz were detected; an upper limit was obtained for H3O+. OH+ and H2O+ are observed purely in absorption, showing a narrow component at the source velocity of 9 km s-1, and a broad blueshifted absorption similar to that reported recently for HF and para-H218O, and attributed to the low velocity outflow of Orion KL. We estimate column densities of OH+ and H2O+ for the 9 km s-1 component of 9 ± 3 × 1012 cm-2 and 7 ± 2 × 1012 cm-2, and those in the outflow of 1.9 ± 0.7 × 1013 cm-2 and 1.0 ± 0.3 × 1013 cm-2. Upper limits of 2.4 × 1012 cm-2 and 8.7 × 1012 cm-2 were derived for the column densities of ortho and para-H3O+ from transitions near 985 and 1657 GHz. The column densities of the three ions are up to an order of magnitude lower than those obtained from recent observations of W31C and W49N. The comparatively low column densities may be explained by a higher gas density despite the assumption of a very high ionization rate.

Mots clés: astrochemistry; molecular processes; line: identification; ISM: abundances; submillimeter: ISM; stars: winds; outflows

Domaines: Astrophysique galactique [astro-ph.GA]; Astrophysique galactique [astro-ph.GA]

H. C. Gupta, P. Rimmer, J. C. Pearson, S. Yu, E. Herbst, et al.. Detection of OH+ and H2O+ towards Orion KL. Astronomy and Astrophysics - A&A, 2010, 521, pp.L47. ⟨10.1051/0004-6361/201015117⟩. ⟨hal-00633387⟩