Astronomical identification of CN^-, the smallest observed molecular anion
By M. Agúndez, J. Cernicharo, M. Guélin, C. Kahane, E. Roueff, J. Kłos, F. Aoiz, F. Lique, N. Marcelino, J. Goicoechea and 4 more. 2010
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We present the first astronomical detection of a diatomic negative ion, the cyanide anion CN-, as well as quantum mechanical calculations of the excitation of this anion through collisions with para-H2. CN- is identified through the observation of the J = 2-1 and J = 3-2 rotational transitions in the C-star envelope IRC +10216 with the IRAM 30-m telescope. The U-shaped line profiles indicate that CN-, like the large anion C6H-, is formed in the outer regions of the envelope. Chemical and excitation model calculations suggest that this species forms from the reaction of large carbon anions with N atoms, rather than from the radiative attachment of an electron to CN, as is the case for large molecular anions. The unexpectedly large abundance derived for CN-, 0.25 % relative to CN, makes likely its detection in other astronomical sources. A parallel search for the small anion C2H- remains so far unconclusive, despite the previous tentative identification of the J = 1-0 rotational transition. The abundance of C2H- in IRC +10216 is found to be vanishingly small, < 0.0014 % relative to C2H.
Subfields: Astronomy and Astrophysics, Instrumentation
View Paper: https://www.semanticscholar.org/paper/0aa010b39ec4d9edea16cd2d5b72f41686bd49f4
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Citations in the corpus
- 2018 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules (2018, methodology): “CN– (cyanide anion) The detection of CN– was reported by Agúndez et al. (2010) in observations of IRC+10216 using the IRAM 30-m telescope.”