Herschel/HIFI discovery of interstellar chloronium (H2Cl+)

D. C. Lis (1) , J. C. Pearson (2) , D. A. Neufeld , P. Schilke (3, 4) , H. S. P. Müller , H. C. Gupta (5) , T. A. Bell , C. Comito (4) , T. G. Phillips (1) , E. A. Bergin (6) , C. Ceccarelli (7) , P. F. Goldsmith , G. A. Blake (8) , A. Bacmann (9) , Alain Baudry (9) , M. Benedettini (7) , A. Benz , J. Black (10) , A. Boogert (7) , S. Bottinelli (11) , S. Cabrit (12) , P. Caselli (13) , Alain Castets (7) , E. Caux (11, 11) , J. Cernicharo (14) , C. Codella (7) , A. Coutens (7) , N. Crimier (7) , N. R. Crockett , F. Daniel (12, 14, 15) , K. Demyk (7) , C. Dominic , M.-L. Dubernet (12) , M. Emprechtinger (16) , P. Encrenaz (12) , E. Falgarone (17) , A. Fuente (7) , M. Gerin (12, 17) , T. F. Giesen , J. R. Goicoechea (12) , F. Helmich (7) , P. Hennebelle (7) , Th. Henning (18) , E. Herbst (19, 20) , Pierre Hily-Blant (7) , Å. Hjalmarson (21) , D. Hollenbach , T. Jacq (9) , C. Joblin (11) , D. Johnstone (22) , C. Kahane (7) , M. Kama (7) , M. Kaufman , A. Klotz (11, 23) , W. D. Langer , B. Larsson (7) , J. Le Bourlot , B. Lefloch (7) , F. Le Petit , D. Li (24) , R. Liseau (2) , S. D. Lord , A. Lorenzani (13) , S. Maret (7) , P. G. Martin (25) , G. J. Melnick (26) , K. M. Menten (27) , P. Morris (28) , J. A. Murphy , Z. Nagy (29) , B. Nisini (30) , V. Ossenkopf (31, 32) , S. Pacheco (7) , L. Pagani (12) , B. Parise (11) , M. Pérault (12) , R. Plume (33) , S.-L. Qin , E. Roueff (31) , M. Salez (7) , A. Sandqvist (34) , P. Saraceno (35) , S. Schlemmer (3) , K. Schuster (7) , R. Snell , J. Stutzki (3) , A. Tielens , N. Trappe (36) , F. F. S. van Der Tak (37, 32) , M. H. D. van Der Wiel , E. van Dishoeck (38) , C. Vastel (11, 11) , S. Viti (7) , Valentine Wakelam (39) , A. Walters (7) , S. Wang (6) , F. Wyrowski (27) , H. W. Yorke , S. Yu (5) , J. Zmuidzinas (16) , Y. Delorme (12) , J.-P. Desbat , R. Güsten (4) , J.-M. Krieg (12) , B. Delforge

1 CALTECH - California Institute of Technology
2 FL - foreign laboratories
3 I. Physikalisches Institut [Köln]
4 Max Planck Institute for Radio Astronomy
5 JPL - Jet Propulsion Laboratory
6 Department of Astronomy [Ann Arbor]
7 LAOG - Laboratoire d'Astrophysique de Grenoble
8 LOCIE - LabOratoire proCédés énergIe bâtimEnt
9 FORMATION STELLAIRE 2010
10 IUCF - Indiana University Cyclotron Facility
11 CESR - Centre d'étude spatiale des rayonnements
12 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
13 OAA - INAF - Osservatorio Astrofisico di Arcetri
14 CAB - Centro de Astrobiologia [Madrid]
15 ENS-PSL - École normale supérieure - Paris
16 Cahill Center for Astronomy and Astrophysics
17 LRA - Laboratoire de Radioastronomie
18 MPIA - Max-Planck-Institut für Astronomie
19 Ohio State Univ, Dept Phys, Columbus, OH 43210 USA
20 Ohio State Univ, Dept Astron & Chem, Columbus, OH 43210 USA
21 Onsala Space Observatory
22 Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V9E 2E7 Canada
23 OHP - Observatoire de Haute-Provence
24 SIMaP - Science et Ingénierie des Matériaux et Procédés
25 LM2C - Laboratoire de Modélisation Multi-échelles des Combustibles
26 CfA - Harvard-Smithsonian Center for Astrophysics
27 MPIFR - Max-Planck-Institut für Radioastronomie
28 IPAC - Infrared Processing and Analysis Center
29 IGBMC - Institut de Génétique et de Biologie Moléculaire et Cellulaire
30 OAR - INAF - Osservatorio Astronomico di Roma
31 LUTH (UMR_8102) - Laboratoire Univers et Théories
32 SRON - SRON Netherlands Institute for Space Research
33 Department of Physics and Astronomy [Calgary]
34 Stockholm Observatory Department of Astronomy
35 IFSI - Istituto di Fisica dello Spazio Interplanetario
36 LDAR (EA_4434) - Laboratoire de Didactique André Revuz
37 Kapteyn Astronomical Institute [Groningen]
38 Leiden Observatory [Leiden]
39 AMOR 2010

We report the first detection of chloronium, H2Cl+, in the interstellar medium, using the HIFI instrument aboard the Herschel Space Observatory. The 212-101 lines of ortho-H_235Cl+ and ortho-H_237Cl+ are detected in absorption towards NGC 6334I, and the 111-000 transition of para-H_235Cl+ is detected in absorption towards NGC 6334I and Sgr B2(S). The H2Cl+ column densities are compared to those of the chemically-related species HCl. The derived HCl/H2Cl+ column density ratios, ~1-10, are within the range predicted by models of diffuse and dense photon dominated regions (PDRs). However, the observed H2Cl+ column densities, in excess of 1013 cm-2, are significantly higher than the model predictions. Our observations demonstrate the outstanding spectroscopic capabilities of HIFI for detecting new interstellar molecules and providing key constraints for astrochemical models. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Table 1 and acknowledgments (page 5) are only available in electronic form at http://www.aanda.org

Mots clés: astrochemistry; line: identification; ISM: abundances; ISM: molecules; molecular processes; submillimetre: ISM

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

D. C. Lis, J. C. Pearson, D. A. Neufeld, P. Schilke, H. S. P. Müller, et al.. Herschel/HIFI discovery of interstellar chloronium (H2Cl+). Astronomy and Astrophysics - A&A, 2010, 521, pp.L9. ⟨10.1051/0004-6361/201014959⟩. ⟨hal-00633439⟩