Nitrogen hydrides in interstellar gas: Herschel/HIFI observations towards G10.6-0.4 (W31C)

C. M. Persson , J. H. Black , J. Cernicharo (1) , J. R. Goicoechea (2) , G. E. Hassel , E. Herbst (3) , M. Gerin (2, 4) , M. de Luca (2) , T. A. Bell , A. Coutens (5) , E. Falgarone (4) , P. F. Goldsmith , H. C. Gupta (6) , M. Kazmierczak , D. C. Lis (7) , B. Mookerjea (8) , D. A. Neufeld , Justin Pearson (5) , T. G. Phillips (7) , P. Sonnentrucker , J. Stutzki (5) , C. Vastel (9) , S. Yu , F. Boulanger (10) , E. Dartois (10) , P. Encrenaz (2) , T. R. Geballe , T. Giesen , B. Godard , C. Gry (11) , P. Hennebelle (5) , Pierre Hily-Blant (5) , C. Joblin (9) , R. Kolos , J. Krelowski , J. Martin-Pintado (5) , K. Menten , R. Monje , M. Perault (4) , R. Plume , M. Salez (5) , S. Schlemmer , M. Schmidt (12) , D. Teyssier (13) , I. Peron , Ph. Cais (14, 15, 16, 17) , A. Cros , L. Ravera (9) , P. Morris , S. Lord (5) , P. Planesas , S. Gauffre (14, 15, 16, 17)

1 CSIC - Centro de Investigaciones Biológicas
2 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
3 OSU - Ohio State University [Columbus]
4 LRA - Laboratoire de Radioastronomie
5 LAOG - Laboratoire d'Astrophysique de Grenoble
6 IIT Delhi - Indian Institute of Technology Delhi
7 CALTECH - California Institute of Technology
8 KOSMA, I. Physikalisches Institut
9 CESR - Centre d'étude spatiale des rayonnements
10 IAS - Institut d'astrophysique spatiale
11 LAM - Laboratoire d'Astrophysique de Marseille
12 Department of Obstetrics and Gynecology
13 Herschel Science Center [Madrid]
14 L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux
15 UB - Université Sciences et Technologies - Bordeaux 1
16 OASU - Observatoire aquitain des sciences de l'univers
17 LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac]

The HIFI instrument on board the Herschel Space Observatory has been used to observe interstellar nitrogen hydrides along the sight-line towards G10.6-0.4 in order to improve our understanding of the interstellar chemistry of nitrogen. We report observations of absorption in NH N=1-0, J=2-1 and ortho-NH2 1_1,1-0_0,0. We also observed ortho-NH3 1_0-0_0, and 2_0-1_0, para-NH3 2_1-1_1, and searched unsuccessfully for NH+. All detections show emission and absorption associated directly with the hot-core source itself as well as absorption by foreground material over a wide range of velocities. All spectra show similar, non-saturated, absorption features, which we attribute to diffuse molecular gas. Total column densities over the velocity range 11-54 km/s are estimated. The similar profiles suggest fairly uniform abundances relative to hydrogen, approximately 6*10^-9, 3*10^-9, and 3*10^-9 for NH, NH2, and NH3, respectively. These abundances are discussed with reference to models of gas-phase and surface chemistry.

Mots clés: Astrophysics; Galaxy Astrophysics; Astrophysics

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]; Astrophysique stellaire et solaire [astro-ph.SR]

C. M. Persson, J. H. Black, J. Cernicharo, J. R. Goicoechea, G. E. Hassel, et al.. Nitrogen hydrides in interstellar gas: Herschel/HIFI observations towards G10.6-0.4 (W31C). Astronomy and Astrophysics - A&A, 2010, 521, pp.id.L45. ⟨10.1051/0004-6361/201015105⟩. ⟨hal-00521649⟩