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Triply deuterated ammonia in NGC 1333

van der Tak, F. F. S. and Schilke, P. and Müller, H. S. P. and Lis, D. C. and Phillips, T. G. and Gerin, M. and Roueff, E. (2002) Triply deuterated ammonia in NGC 1333. Astronomy & Astrophysics, 388 (3). L53-L56. ISSN 0004-6361. doi:10.1051/0004-6361:20020647.

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The Caltech Submillimeter Observatory has detected triply deuterated ammonia, ND_3, through its J_K = 1^a_0 → 0^s_0 transition near 310 GHz. Emission is found in the NGC 1333 region, both towards IRAS 4A and a position to the South-East where DCO^+ peaks. In both cases, the hyperfine ratio indicates that the emission is optically thin. Column densities of ND_3 are 3-6 x 10^(11) cm^(-2) for T_(ex) = 10 K and twice as high for T_(ex) = 5 K. Using a Monte Carlo radiative transfer code and a model of the structure of the IRAS source with temperature and density gradients, the estimated ND_3 abundance is 3.2 x 10^(-12) if ND_3/H_2 is constant throughout the envelope. In the more likely case that ND_3/H_2D^+ is constant, ND_3/H_2 peaks in the cold outer parts of the source at a value of 1.0 x 10^(-11). To reproduce the observed NH_3/ND_3 abundance ratio of ~1000, grain surface chemistry requires an atomic D/H ratio of ≈0.15 in the gas phase, >10 times higher than in recent chemical models. More likely, the deuteration of NH_3 occurs by ion-molecule reactions in the gas phase, in which case the data indicate that deuteron transfer reactions are much faster than proton transfers.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Schilke, P.0000-0003-2141-5689
Müller, H. S. P.0000-0002-0183-8927
Lis, D. C.0000-0002-0500-4700
Roueff, E.0000-0002-4949-8562
Additional Information:© 2002 ESO. Received: 1 April 2002. Accepted: 24 April 2002. The CSO is supported by NSF grant AST 99-80846. HSPM acknowledges support from the Deutsche Forschungsgemeinschaft (DFG) via grant SFB 494.
Funding AgencyGrant Number
NSFAST 99-80846
Deutsche Forschungsgemeinschaft (DFG)SFB 494
Subject Keywords:ISM: abundances - ISM: molecules
Issue or Number:3
Record Number:CaltechAUTHORS:20180207-110552669
Persistent URL:
Official Citation:Triply deuterated ammonia in NGC 1333 F. F. S. van der Tak, P. Schilke, H. S. P. Müller, D. C. Lis, T. G. Phillips, M. Gerin and E. Roueff A&A, 388 3 (2002) L53-L56 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84716
Deposited By: Ruth Sustaita
Deposited On:08 Feb 2018 16:21
Last Modified:15 Nov 2021 20:22

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