Planetary formation and water delivery in the habitable zone around solar-type stars in different dynamical environments

TL;DR

This study investigates how different dynamical environments influence the formation and water delivery of habitable zone planets around solar-type stars, revealing that water-rich planets are commonly formed but Earth-like planets are rarer.

Contribution

It combines semi-analytical modeling and N-body simulations to analyze planet formation and water delivery across various dynamical scenarios around Sun-like stars.

Findings

Water worlds form efficiently in the habitable zone across scenarios.

Giant planets influence the migration and water content of forming planets.

Earth-like planets with similar mass and water content are rare around solar-type stars.

Abstract

Aims. We study the formation and water delivery of planets in the habitable zone (HZ) around solar-type stars. In particular, we study different dynamical environments that are defined by the most massive body in the system. Methods. First of all, a semi-analytical model was used to define the mass of the protoplanetary disks that produce each of the five dynamical scenarios of our research. Then, we made use of the same semi-analytical model to describe the evolution of embryos and planetesimals during the gaseous phase. Finally, we carried out N-body simulations of planetary accretion in order to analyze the formation and water delivery of planets in the HZ in the different dynamical environments. Results. Water worlds are efficiently formed in the HZ in different dynamical scenarios. In systems with a giant planet analog to Jupiter or Saturn around the snow line, super-Earths tend to migrate into the HZ from outside the snow line as a result of interactions with other embryos and accrete water only during the gaseous phase. In systems without giant planets, Earths and super-Earths with high water by mass contents can either be formed in situ in the HZ or migrate into it from outer regions, and water can be accreted during the gaseous phase and in collisions with water-rich embryos and planetesimals. Conclusions. The formation of planets in the HZ with very high water by mass contents seems to be a common process around Sun- like stars. Our research suggests that such planets are still very efficiently produced in different dynamical environments. Moreover, our study indicates that the formation of planets in the HZ with masses and water contents similar to those of Earth seems to be a rare process around solar-type stars in the systems under consideration.