@Article{Maret_etal2010,
author="Maret, S.
and Bacmann, A.
and Bottinelli, S.
and Parise, B.
and Caux, E.
and Faure, A.
and Bergin, E. A.
and Blake, G. A.
and Castets, A.
and Ceccarelli, C.
and Cernicharo, J.
and Coutens, A.
and Crimier, N.
and Demyk, K.
and Dominik, C.
and Gerin, M.
and Hennebelle, P.
and Henning, T.
and Kahane, C.
and Klotz, A.
and Melnick, G.
and Pagani, L.
and Schilke, P.
and Vastel, C.
and Wakelam, V.
and Walters, A.
and Baudry, A.
and Bell, T.
and Benedettini, M.
and Boogert, A.
and Cabrit, S.
and Caselli, P.
and Codella, C.
and Comito, C.
and Encrenaz, P.
and Falgarone, E.
and Fuente, A.
and Goldsmith, P. F.
and Helmich, F.
and Herbst, E.
and Jacq, T.
and Kama, M.
and Langer, W.
and Lefloch, B.
and Lis, D.
and Lord, S.
and Lorenzani, A.
and Neufeld, D.
and Nisini, B.
and Pacheco, S.
and Phillips, T.
and Salez, M.
and Saraceno, P.
and Schuster, K.
and Tielens, X.
and van der Tak, F.
and van der Wiel, M. H. D.
and Viti, S.
and Wyrowski, F.
and Yorke, H.",
title="Nitrogen hydrides in the cold envelope of IRAS 16293-2422",
journal="Astron. Astrophys.",
year="2010",
volume="521",
pages="L52",
optkeywords="HEB mixer applications; HIFI; Herschel; ISM: abundances / ISM: general / astrochemistry",
abstract="Nitrogen is the fifth most abundant element in the Universe, yet the gas-phase chemistry of N-bearing species remains poorly understood. Nitrogen hydrides are key molecules of nitrogen chemistry. Their abundance ratios place strong constraints on the production pathways and reaction rates of nitrogen-bearing molecules. We observed the class 0 protostar IRAS 16293-2422 with the heterodyne instrument HIFI, covering most of the frequency range from 0.48 to 1.78 THz at high spectral resolution. The hyperfine structure of the amidogen radical o-NH2 is resolved and seen in absorption against the continuum of the protostar. Several transitions of ammonia from 1.2 to 1.8 THz are also seen in absorption. These lines trace the low-density envelope of the protostar. Column densities and abundances are estimated for each hydride. We find that NH:NH2:NH3~{\^a}{\texttenthousand}<2c6>~5:1:300. Dark clouds chemical models predict steady-state abundances of NH2 and NH3 in reasonable agreement with the present observations, whilst that of NH is underpredicted by more than one order of magnitude, even using updated kinetic rates. Additional modelling of the nitrogen gas-phase chemistry in dark-cloud conditions is necessary before having recourse to heterogen processes.",
optnote="exported from refbase (https://db.rplab.ru/refbase/show.php?record=1094), last updated on Fri, 17 Jun 2016 16:56:16 -0500",
doi="10.1051/0004-6361/201015253",
opturl="https://doi.org/10.1051/0004-6361/201015253"
}