The New Generation Planetary Population Synthesis (NGPPS). II. Planetary population of solar-like stars and overview of statistical results

TL;DR

This study uses the Bern model to synthesize planetary populations around solar-like stars, analyzing how initial embryo numbers and metallicity influence planetary demographics and providing comprehensive insights into planetary system formation.

Contribution

It introduces a detailed planetary population synthesis with varying initial embryo counts, offering new insights into the effects of initial conditions and metallicity on planetary demographics.

Findings

Giant planet properties are stable with at least 10 embryos per system.

Only populations with 100 embryos can produce terrestrial planets reaching the giant-impact stage.

Frequency of terrestrial planets peaks at [Fe/H] of -0.2, super-Earths at 0.0, and giant planets increase with [Fe/H].

Abstract

We want to understand global observable consequences of different physical processes and initial properties on the demographics of the planetary population. We use the Generation III Bern model to perform planetary population synthesis. We synthesise five populations with each a different initial number of Moon-mass embryos per disc: 1, 10, 20, 50, and 100. The last is our nominal population around 1 Sun-mass stars. The properties of giant planets do not change much as long as there are at least 10 embryos in each system. The study of giants can thus be done with simulations requiring less computational resources. For inner terrestrial planets, only the 100-embryos population is able to attain the giant-impact stage. In that population, each planetary system contains on average 8 planets more massive than 1 $M_\oplus$. The fraction of systems with giants planets at all orbital distances is 18%, but only 1.6% are at > 10 au. Systems with giants contain on average 1.6 such planets. The frequency of terrestrial and super-Earth planets peaks at a stellar [Fe/H] of -0.2 and 0.0, respectively, being limited at lower [Fe/H] by a lack of building blocks, and by (for them) detrimental growth of more massive dynamically active planets at higher [Fe/H]. The frequency of more massive planets (Neptunian, giants) increases monotonically with [Fe/H]. The fast migration of planets in the 5-50 $M_\oplus$ range is reduced by the presence of multiple lower-mass inner planets in the multi-embryos populations. We present one of the most comprehensive simulations of (exo)planetary system formation and evolution to date. For theory, they provide the framework to observationally test the global statistical consequences of theoretical models for specific physical processes. This is a important ingredient towards the development of a standard model of planetary formation and evolution.