Delivery of icy planetesimals to inner planets in the Proxima Centauri planetary system

TL;DR

This study estimates the delivery of icy planetesimals from Proxima Centauri c to inner planets b and d, suggesting significant water transfer that could exceed Earth's ocean mass, based on dynamical simulations of planetesimal trajectories.

Contribution

It provides new estimates of icy planetesimal delivery to inner planets in the Proxima Centauri system using detailed dynamical modeling.

Findings

Total mass of planetesimals in feeding zone: 10-15 Earth masses.

Mass of material delivered to planet b: 0.002-0.015 Earth masses.

Water delivery to planet b likely exceeds Earth's oceans.

Abstract

The estimates of the delivery of icy planetesimals from the feeding zone of Proxima Centauri c (with mass equal to 7mE, mE is the mass of the Earth) to inner planets b and d were made. They included the studies of the total mass of planetesimals in the feeding zone of planet c and the probabilities of collisions of such planetesimals with inner planets. This total mass could be about 10-15mE. It was estimated based on studies of the ratio of the mass of planetesimals ejected into hyperbolic orbits to the mass of planetesimals collided with forming planet c. At integration of the motion of planetesimals, the gravitational influence of planets c and b and the star was taken into account. In most series of calculations, planetesimals collided with planets were excluded from integrations. Based on estimates of the mass of planetesimals ejected into hyperbolic orbits, it was concluded that during the growth of the mass of planet c the semi-major axis of its orbit could decrease by at least a factor of 1.5. Depending on possible gravitational scattering due to mutual encounters of planetesimals, the total mass of material delivered by planetesimals from the feeding zone of planet c to planet b was estimated to be between 0.002mE and 0.015mE. Probably, the amount of water delivered to Proxima Centauri b exceeded the mass of water in Earth's oceans. The amount of material delivered to planet d could be a little less than that delivered to planet b.