Year: 2019
Type: article
Abstract: 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, 15 N/ 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 15 N during the Archean era. Comets have a higher 15 N/ 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 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 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.
Source: The Astronomical Journal
Authors: Cheng Chen, Jeremy L. Smallwood, Rebecca G. Martin, Mario Livio
Institution: University of Nevada, Las Vegas
Language: English
Topic: Astro and Planetary Science
Subfield: Space and Planetary Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2903745900