Herschel observations of EXtra-Ordinary Sources (HEXOS): The present and future of spectral surveys with Herschel/HIFI

E. A. Bergin (1) , T. G. Phillips (2) , C. Comito (3) , N. R. Crockett , D. C. Lis (2) , P. Schilke (3, 4) , S. Wang (1) , T. A. Bell , G. A. Blake (5) , B. Bumble , E. Caux (6, 6) , S. Cabrit (7) , C. Ceccarelli (8) , J. Cernicharo (9) , F. Daniel (7, 9, 10) , Th. de Graauw (11) , M.-L. Dubernet (7) , M. Emprechtinger (12) , P. Encrenaz (7) , E. Falgarone (13) , M. Gerin (7, 13) , T. F. Giesen , J. R. Goicoechea (7) , P. F. Goldsmith , H. C. Gupta (14) , P. Hartogh (15) , F. P. Helmich (11) , E. Herbst (16, 17) , C. Joblin (6) , D. Johnstone (18) , J. H. Kawamura , W. D. Langer , W. B. Latter , S. D. Lord , S. Maret (8) , P. G. Martin (19) , G. J. Melnick (20) , K. M. Menten (21) , P. Morris (22) , H. S. P. Müller , J. A. Murphy , D. A. Neufeld , V. Ossenkopf (23, 24) , L. Pagani (7) , J. C. Pearson (11) , M. Pérault (7) , R. Plume (25) , P. Roelfsema , S.-L. Qin , M. Salez (8) , S. Schlemmer (4) , J. Stutzki (4) , A. G. G. M. Tielens (24) , N. Trappe (26) , F. F. S. van Der Tak (24, 27) , C. Vastel (6, 6) , H. W. Yorke , S. Yu (14) , J. Zmuidzinas (12)

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

We present initial results from the Herschel GT key program: Herschel observations of EXtra-Ordinary Sources (HEXOS) and outline the promise and potential of spectral surveys with Herschel/HIFI. The HIFI instrument offers unprecedented sensitivity, as well as continuous spectral coverage across the gaps imposed by the atmosphere, opening up a largely unexplored wavelength regime to high-resolution spectroscopy. We show the spectrum of Orion KL between 480 and 560 GHz and from 1.06 to 1.115 THz. From these data, we confirm that HIFI separately measures the dust continuum and spectrally resolves emission lines in Orion KL. Based on this capability we demonstrate that the line contribution to the broad-band continuum in this molecule-rich source is ~20-40% below 1 THz and declines to a few percent at higher frequencies. We also tentatively identify multiple transitions of HD18O in the spectra. The first detection of this rare isotopologue in the interstellar medium suggests that HDO emission is optically thick in the Orion hot core with HDO/H2O ~ 0.02. We discuss the implications of this detection for the water D/H ratio in hot cores. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Figure 2 (page 6) is also available in electronic form at http://www.aanda.org

Mots clés: ISM: abundances; ISM: molecules; submillimeter: ISM

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

E. A. Bergin, T. G. Phillips, C. Comito, N. R. Crockett, D. C. Lis, et al.. Herschel observations of EXtra-Ordinary Sources (HEXOS): The present and future of spectral surveys with Herschel/HIFI. Astronomy and Astrophysics - A&A, 2010, 521, pp.L20. ⟨10.1051/0004-6361/201015071⟩. ⟨hal-00633429⟩