A Compound model for the origin of Earth's water

TL;DR

This paper proposes a combined model for Earth's water origin, integrating endogenous and exogenous sources, and uses numerical simulations to evaluate their contributions during planet formation.

Contribution

It introduces a novel compound model that combines multiple water sources and assesses their roles in Earth's water delivery through simulations.

Findings

The compound model shows improved water delivery timing and quantity for Earth-like planets.

Simulations suggest multiple sources contributed to Earth's water, with some cometary input.

The study compares different water distribution models and analyzes isotopic ratios.

Abstract

One of the most important subjects of debate in the formation of the solar system is the origin of Earth's water. Comets have long been considered as the most likely source of the delivery of water to Earth. However, elemental and isotopic arguments suggest a very small contribution from these objects. Other sources have also been proposed, among which, local adsorption of water vapor onto dust grains in the primordial nebula and delivery through planetesimals and planetary embryos have become more prominent. However, no sole source of water provides a satisfactory explanation for Earth's water as a whole. In view of that, using numerical simulations, we have developed a compound model incorporating both the principal endogenous and exogenous theories, and investigating their implications for terrestrial planet formation and water-delivery. Comets are also considered in the final analysis, as it is likely that at least some of Earth's water has cometary origin. We analyze our results comparing two different water distribution models, and complement our study using D/H ratio, finding possible relative contributions from each source, focusing on planets formed in the habitable zone. We find that the compound model play an important role by showing more advantage in the amount and time of water-delivery in Earth-like planets.