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

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 × 10^-3 (that is, ≈40% poorer in ¹⁵N relative to terrestrial atmosphere). The ¹⁵N/¹⁴N ratio of the protosolar nebula was 2.27 ± 0.03 × 10^-3, 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.