The puzzling nitrogen isotopic composition of comets

Séminaire IPAG de Susanne Wampfler (CSH Bern), jeudi 9 mai 2019 à 11h00, salle Manuel Forestini

Constraining the origin of different solar system materials is critical for understanding the formation and evolution of our solar system. One of the puzzling properties of our solar system is that the isotopic composition of volatile elements like nitrogen is heterogeneous among the solar system bodies. For instance, the terrestrial planets, comets, and meteorites are significantly enriched in the rare 15N-isotope compared to the Sun and the gas giants. While the existence of this isotopic anomaly is well established, its origin is still a big open question. Because the highest 15N-enrichments are associated with some of the most pristine materials, namely cometary ices and meteorites, they were most likely inherited from the early phases of solar system formation. Understanding the origin of this isotopic anomaly will therefore help in better constraining the formation region, time, and mechanisms through which this cometary and meteoritic matter formed.

I will present measurements of the nitrogen isotopic composition in the gas around young stars from (submillimeter observations, as well as results on the nitrogen isotopes in comet 67P from the in-situ measurement by Rosetta-ROSINA. I will also discuss how we are trying to link the results from astrochemistry, planetary science, and cosmochemistry to gain insights into the origin of the nitrogen isotope anomaly in the solar system.