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

作者：Persson C M^*; Black J H; Cernicharo J; Goicoechea J R; Hassel G E; Herbst E; Gerin M; De Luca M; Bell T A; Coutens A; Falgarone E; Goldsmith P F; Gupta H; Kazmierczak M; Lis D C; Mookerjea B; Neufeld D A; Pearson J; Phillips T G; Sonnentrucker P; Stutzki J; Vastel C; Yu S; Boulanger F; Dartois E; Encrenaz P; Geballe T R; Giesen T; Godard B; Gry C; Hennebelle P; Hily Blant P; Joblin C; Kolos R; Krelowski J

来源：Astronomy & Astrophysics, 2010, 521: L45.

DOI：10.1051/0004-6361/201015105

• astrochemistry
• ISM: abundances
• ISM: molecules
• molecular processes
• submillimetre: ISM
• line: formation

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(-1) are estimated. The similar profiles suggest fairly uniform abundances relative to hydrogen, approximately 6 x 10(-9), 3 x 10(-9), and 3 x 10(-9) for NH, NH2, and NH3, respectively. These abundances are discussed with reference to models of gas-phase and surface chemistry.

• 出版日期2010-10