Philippe Rousselot¹, Olivier Pirali², Emmanuël Jehin³, Michel Vervloet², Damien Hutsemékers³, Jean Manfroid³, Daniel Cordier¹, Marie-Aline Martin-Drumel², Sébastien Gruet², Claude Arpigny³, Alice Decock³, and Olivier Mousis¹

¹Institut UTINAM-UMR CNRS 6213, Observatoire des Sciences de l’Univers THETA, University of Franche-Comté, BP 1615, F-25010 Besançon Cedex, France
²Synchrotron SOLEIL, ligne AILES, UMR 8214 CNRS, L’orme des Merisiers, Saint-Aubin, F-91192 Gif-Sur-Yvette, France
³Département d’Astrophysique, de Géophysique et d’Océanographie, Université de Liège, Allée du Six Aohat ut, B-4000 Liège, Belgium

Determination of the nitrogen isotopic ratios in different bodies of the solar system provides important information regarding the solar system’s origin. We unambiguously identified emission lines in comets due to the ¹⁵NH₂ radical produced by the photodissociation of ¹⁵NH₃. Analysis of our data has permitted us to measure the ¹⁴N/¹⁵N isotopic ratio in comets for a molecule carrying the amine (–NH) functional group. This ratio, within the error, appears similar to that measured in comets in the HCN molecule and the CN radical, and lower than the protosolar value, suggesting that N₂ and NH₃ result from the separation of nitrogen into two distinct reservoirs in the solar nebula. This ratio also appears similar to that measured in Titan’s atmospheric N₂, supporting the hypothesis that, if the latter is representative of its primordial value in NH₃, these bodies were assembled from building blocks sharing a common formation location.

Reference
Rousselot P, Pirali O, Jehin E, Vervloet M, Hutsemékers D, Manfroid J, Cordier D, Martin-Drumel M-A, Gruet S, Arpigny C, Decock A and Mousis O (2014) Toward a Unique Nitrogen Isotopic Ratio in Cometary Ices. The Astrophysical Journal – Letters 780:L17.
[doi:10.1088/2041-8205/780/2/L17]

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