Late Delivery of Nitrogen to the Earth
- Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Box 454002, Las Vegas, NV 89154 (United States)
Atmospheric nitrogen may be a necessary ingredient for the habitability of a planet as its presence helps to prevent water loss from a planet. The present-day nitrogen isotopic ratio, {sup 15}N/{sup 14}N, in the Earth’s atmosphere is a combination of the primitive Earth’s ratio and the ratio that might have been delivered in comets and asteroids. Asteroids have a nitrogen isotopic ratio that is close to the Earth’s. This indicates either a similar formation environment to the Earth or that the main source of nitrogen was delivery by asteroids. However, according to geological records, the Earth’s atmosphere could have been enriched in {sup 15}N during the Archean era. Comets have a higher {sup 15}N/{sup 14}N ratio than the current atmosphere of the Earth, and we find that about 5% ∼ 10% of nitrogen in the atmosphere of the Earth may have been delivered by comets to explain the current atmosphere of the Earth or the enriched {sup 15}N atmosphere of the Earth. We model the evolution of the radii of the snow lines of molecular nitrogen and ammonia in a protoplanetary disk and find that both have radii that put them farther from the Sun than the main asteroid belt. With an analytic secular resonance model and N-body simulations we find that the ν {sub 8} apsidal precession secular resonance with Neptune, which is located in the Kuiper Belt, is a likely origin for the nitrogen-delivering comets that impact the Earth.
- OSTI ID:
- 22897284
- Journal Information:
- The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 2 Vol. 157; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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