Nitrogen isotope variations in the solar system

International audienceThe relative proportion of the two isotopes of nitrogen (14N and 15N) shows dramatic variations among the different solar system objects and reservoirs. NASA's Genesis mission, which provided the first direct sample of the solar wind, confirmed that the Sun, and by inference the protosolar nebula, is highly depleted in the heavy 15N isotope. The inner planets, asteroids, and comets are enriched in 15N by tens to 5 hundreds of percent, with organic matter in primitive meteorites recording the most extreme 15N/14 N ratios. Several lines of evidence suggest that these 15N enrichments were not inherited from presolar material but are, instead, the result of N isotope fractionation processes that occurred early in solar system history. Together, these observations indicate that N isotopes are a powerful tool to investigate early material processing and large-scale disk dynamics as well as planetary formation processes. In addition, N isotopes are the tracer of choice to investigate the origin and evolution of planetary atmospheres