A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples

Bernard Marty Centre de Recherches Pétrographiques et Géochimiques (CRPG), Nancy Université, France
Marc Chaussidon Centre de Recherches Pétrographiques et Géochimiques (CRPG), Nancy Université, France
R.C. Wiens Los Alamos National Laboratory, Los Alamos, USA
A.J.G. Jurewicz School of Earth and Space Exploration, Arizona State University, USA
D.S. Burnett Department of Geological and Planetary Sciences, California Institute of Technology, USA

Science 332, 1533-1536. doi:10.1126/science.1204656
Date de publication : 24 juin 2011

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The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a 15N/14N ratio of 2.18 ± 0.02 x 103 (that is, ~ 40% poorer in 15N relative to terrestrial atmosphere). The 15N/14N ratio of the protosolar nebula was 2.27 ± 0.03 x 103, which is the lowest 15N/14N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the 15N-depleted components observed in solar system reservoirs.

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