An impact-free mechanism to deliver water to terrestrial planets and exoplanets

Vol. 692
10. Planets, planetary systems, and small bodies

An impact-free mechanism to deliver water to terrestrial planets and exoplanets

It is usually assumed that water was delivered to Earth by impactors. In this study, the authors address the possibility that water was delivered by a viscous gaseous disk. The water present in this disk would have itself been the result of sublimation of the ice on asteroids. To perform this study, the authors developed a new model of sublimation that takes into consideration the variable luminosity of the early Sun. Then they ran a numerical code that simulates the evolution of the viscous gaseous disk.

This study shows the efficiency of this mechanism, which implies that most of the water on Earth was delivered between 20 and 30 Myr after the birth of the Sun. It also suggests that this new mechanism of water delivery is more generic than the impact scenario. Such watery disks could be detected in young exo-asteroid belts with ALMA.