New insights on Saturn's formation from its nitrogen isotopic composition

Abstract

The recent derivation of a lower limit for the ${}^{14}$N/${}^{15}$N ratio in Saturn's ammonia, which is found to be consistent with the Jovian value, prompted us to revise models of Saturn's formation using as constraints the supersolar abundances of heavy elements measured in its atmosphere. Here we find that it is possible to account for both Saturn's chemical and isotopic compositions if one assumes the formation of its building blocks at $\sim$45 K in the protosolar nebula, provided that the O abundance was $\sim$2.6 times protosolar in its feeding zone. To do so, we used a statistical thermodynamic model to investigate the composition of the clathrate phase that formed during the cooling of the protosolar nebula and from which the building blocks of Saturn were agglomerated. We find that Saturn's O/H is at least $\sim$34.9 times protosolar and that the corresponding mass of heavy elements ($\sim$43.1 \Mearth) is within the range predicted by semi-convective interior models.

arXiv commentAccepted for publication in Astrophysical Journal Letters

References in corpus (19)

• The effects of snowlines on C/O in planetary atmospheres
• Accretion Disks around Young Objects. I. The Detailed Vertical Structure
• Abundances of the elements in the solar system
• Imaging of the CO Snow Line in a Solar Nebula Analog
• Evolution of protoplanetary disks: Constraints from DM Tauri and GM Aurigae
• A new vision on giant planet interiors: the impact of double diffusive convection
• Phase Separation in Giant Planets: Inhomogeneous Evolution of Saturn
• On the Evolution of the Snow Line in Protoplanetary Discs
• Spatial mapping of ices in the Oph-F core: A direct measurement of CO depletion and the formation of CO2
• Effects of Helium Phase Separation on the Evolution of Extrasolar Giant Planets
• Determination of the minimum masses of heavy elements in the envelopes of Jupiter and Saturn
• Planetesimal Compositions in Exoplanet Systems
• Clathration of Volatiles in the Solar Nebula and Implications for the Origin of Titan's atmosphere
• Saturn layered structure and homogeneous evolution models with different EOSs
• Carbon-rich planet formation in a solar composition disk
• The Origin of Nitrogen on Jupiter and Saturn from the ${}^{15}$N/${}^{14}$N Ratio
• The measured compositions of Uranus and Neptune from their formation on the CO iceline
• Propagation of the Gravo-Magneto Disc Instability
• The dual origin of the nitrogen deficiency in comets: selective volatile trapping in the nebula and postaccretion radiogenic heating

Cited by in corpus (11)

• Scientific rationale for Uranus and Neptune in situ explorations
• Deep Atmosphere Composition, Structure, Origin, and Exploration, with Particular Focus on Critical in situ Science at the Icy Giants
• A protosolar nebula origin for the ices agglomerated by Comet 67P/Churyumov-Gerasimenko
• Jupiter's formation in the vicinity of the amorphous ice snowline
• A $\sim$32-70 K formation temperature range for the ice grains agglomerated by comet 67P/Churyumov-Gerasimenko
• Evolution of the reservoirs of volatiles in the protosolar nebula
• The deep composition of Uranus and Neptune from in situ exploration and thermochemical modeling
• Sulfurization of Iron in the Dynamic Solar Nebula and Implications for Planetary Compositions
• Juice-SWI during the Lunar-Earth-Gravity-Assist (LEGA) - Part 2: Instrument operations
• Possible formation pathways for the low density Neptune-mass planet HAT-P-26b
• What is Neptune's D/H ratio really telling us about its water abundance ?