The origin and evolution of nitrogen in solar system bodies is an important question for understanding processes that took place during the formation of the planets and solar system bodies. Pluto has an atmosphere that is 99% molecular nitrogen, but it is unclear if this nitrogen is primordial or derived from ammonia in the protosolar nebula. The nitrogen isotope ratio is an important tracer of the origin of nitrogen on solar system bodies, and can be used at Pluto to determine the origin of its nitrogen. After evaluating the potential impact of escape and photochemistry on Pluto’s nitrogen isotope ratio (14N/15N), we find that if Pluto’s nitrogen originated as N2 the current ratio in Pluto’s atmosphere would be greater than 324 while it would be less than 157 if the source of Pluto’s nitrogen were NH3. The New Horizons spacecraft successfully visited the Pluto system in July 2015 providing a potential opportunity to measure 14N/15N in N2.

中文翻译：

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对冥王星氮源和大气逃逸历史的同位素限制

太阳系天体中氮的起源和演化是理解行星和太阳系天体形成过程中发生的过程的一个重要问题。冥王星的大气层中 99% 是分子氮，但尚不清楚这种氮是原始的还是源自原太阳星云中的氨。氮同位素比是太阳系天体氮来源的重要示踪剂，可用于冥王星确定其氮来源。在评估了逃逸和光化学对冥王星氮同位素比（14N/15N）的潜在影响后，我们发现，如果冥王星的氮起源于N2，则冥王星大气中的当前比值将大于324，而如果源头为N2，则冥王星大气中的当前比值将小于157。冥王星的氮是NH3。新视野号航天器于 2015 年 7 月成功访问冥王星系统，提供了测量 N2 中 14N/15N 的潜在机会。