arXiv subjects

Andrin Kessler

Publications and source records attributed to Andrin Kessler.

2 recordsLinked to original sources

arXiv2026

The formation of planetary systems: physics, populations, and architectures

We review the progresses made in global theoretical models of planetary system formation in the last decade using the example of the planetary system formation framework known as the Bern Model that has been continuously developed since before the beginning of the NCCR PlanetS. We highlight major developments and applications that have since been implemented, reflecting important recent advancements of planet formation theory overall, such as MHD wind-driven disk evolution, planetesimal evolution including fragmentation, dust evolution and pebble accretion, formation of planets in structured disks, interior structure models allowing for compositional gradients, as well as the analysis of the emerging planetary system architectures and the identification of different classes of architectures. We discuss how these new models impact the formation and evolution process and translate into different populations of planets and planetary systems. We also discuss the major strengths of the Bern Model, including successful predictions of the break in the planetary mass function at 30 MEarth, the prevalence of low-mass planets, the radius pile-up around 1 RJupiter, and the evaporation valley, with the recent New Generation Planetary Population Synthesis models with 100 seeds per disk providing quantitive matches to many RV-survey and Kepler diagnostics. This includes key characteristics of planetary system architectures. We also highlight the limitations of this model, some of them were addressed during the course of the NCCR PlanetS: the inclusion of the early phases of planet formation from dust to planetesimals, the hybrid pebble-planetesimals accretion of solids, simplified interior structure models, reliance on simplified parametrizations that may not encapsulate the full complexity of physical processes, and computational constraints.

astro-ph.EP↗

arXiv2023

The interplay between pebble and planetesimal accretion in population synthesis models and its role in giant planet formation

In the core accretion scenario of planet formation, rocky cores grow by first accreting solids until they are massive enough to accrete gas. For giant planet formation this means that a massive core must form within the lifetime of the gas disk. The accretion of roughly km-sized planetesimals and the accretion of mm-cm sized pebbles are typically discussed separately as the main solid accretion mechanisms. We investigate the interplay between the two accretion processes in a disk containing both pebbles and planetesimals for planet formation in general and in the context of giant planet formation specifically. The goal is to disentangle and understand the fundamental interactions that arise in such hybrid pebble-planetesimal models. We combine a simple model of pebble formation and accretion with a global model of planet formation which considers the accretion of planetesimals. We compare synthetic populations of planets formed in disks composed of different amounts of pebbles and 600 meter sized planetesimals. On a system-level, we study the formation pathway of giant planets in these disks. We find that, in hybrid disks containing both pebbles and planetesimals, the formation of giant planets is strongly suppressed whereas in a pebbles-only or planetesimals-only scenario, giant planets can form. We identify the heating associated with the accretion of up to 100 km sized planetesimals after the pebble accretion period to delay the runaway gas accretion of massive cores. Coupled with strong inward type-I migration acting on these planets, this results in close-in icy sub-Neptunes originating from the outer disk. We conclude that, in hybrid pebble-planetesimal scenarios, the late accretion of planetesimals is a critical factor in the giant planet formation process and that inward migration is more efficient for planets in increasingly pebble dominated disks.

astro-ph.EP↗