NITROGEN ISOTOPIC FRACTIONATION IN INTERSTELLAR AMMONIA

被引:58
|
作者
Lis, D. C. [1 ]
Wootten, A. [2 ]
Gerin, M. [3 ,4 ]
Roueff, E. [5 ]
机构
[1] CALTECH, Cahill Ctr Astron & Astrophys 301 17, Pasadena, CA 91125 USA
[2] Natl Radio Astron Observ, Charlottesville, VA 22903 USA
[3] Observ Paris, CNRS, LERMA, UMR8112, F-75231 Paris 05, France
[4] Ecole Normale Super, F-75231 Paris 05, France
[5] Observ Paris, CNRS, LUTh, Sect Meudon,UMR8102, F-92195 Meudon, France
基金
美国国家科学基金会;
关键词
astrochemistry; ISM: abundances; ISM: individual objects (Barnard 1; NGC; 1333); ISM: molecules; molecular processes; radio lines: ISM; RATIO; CLOUD; ABUNDANCES;
D O I
10.1088/2041-8205/710/1/L49
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Using the Green Bank Telescope, we have obtained accurate measurements of the N-14/N-15 isotopic ratio in ammonia in two nearby cold, dense molecular clouds, Barnard 1 and NGC 1333. The N-14/N-15 ratio in Barnard 1, 334 +/- 50 (3 sigma), is particularly well constrained and falls in between the local interstellar medium/proto-solar value of similar to 450 and the terrestrial atmospheric value of 272. The NGC 1333 measurement is consistent with the Barnard I result, but has a larger uncertainty. We do not see evidence for the very high N-15 enhancement; seen in cometary CN. Sensitive observations of a larger, carefully selected sample of prestellar cores with varying temperatures and gas densities can significantly improve our understanding of the nitrogen fractionation in the local interstellar medium and its relation to the isotopic ratios measured in various solar system reservoirs.
引用
收藏
页码:L49 / L52
页数:4
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