New constraints on the delivery of cometary water and nitrogen to Earth from the N/N isotopic ratio |
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Authors: | Damien Hutsemé kers,Jean Manfroid,Emmanuë l Jehin,Claude Arpigny |
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Affiliation: | a Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 août 17, B-4000 Liège, Belgium b Senior Research Associate Fonds National de la Recherche Scientifique, Belgium c Research Director Fonds National de la Recherche Scientifique, Belgium d Research Associate Fonds National de la Recherche Scientifique, Belgium |
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Abstract: | New independent constraints on the amount of water delivered to Earth by comets are derived using the 15N/14N isotopic ratio, measured to be roughly twice as high in cometary CN and HCN as in the present Earth. Under reasonable assumptions, we find that no more than a few percent of Earth’s water can be attributed to comets, in agreement with the constraints derived from D/H. Our results also suggest that a significant part of Earth’s atmospheric nitrogen might come from comets. Since the 15N/14N isotopic ratio is not different in Oort-cloud and Kuiper-belt comets, our estimates apply to the contribution of both types of objects. |
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Keywords: | Comets Earth Origin, Solar System |
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