Lunar and terrestrial planet formation in the Grand Tack scenario.

Philos Trans A Math Phys Eng Sci

Laboratoire Lagrange, UNSA, OCA, CNRS, Boulevard de l'Observatoire, BP 4029, 06304 Nice Cedex 4, France.

Published: September 2014

We present conclusions from a large number of N-body simulations of the giant impact phase of terrestrial planet formation. We focus on new results obtained from the recently proposed Grand Tack model, which couples the gas-driven migration of giant planets to the accretion of the terrestrial planets. The giant impact phase follows the oligarchic growth phase, which builds a bi-modal mass distribution within the disc of embryos and planetesimals. By varying the ratio of the total mass in the embryo population to the total mass in the planetesimal population and the mass of the individual embryos, we explore how different disc conditions control the final planets. The total mass ratio of embryos to planetesimals controls the timing of the last giant (Moon-forming) impact and its violence. The initial embryo mass sets the size of the lunar impactor and the growth rate of Mars. After comparing our simulated outcomes with the actual orbits of the terrestrial planets (angular momentum deficit, mass concentration) and taking into account independent geochemical constraints on the mass accreted by the Earth after the Moon-forming event and on the time scale for the growth of Mars, we conclude that the protoplanetary disc at the beginning of the giant impact phase must have had most of its mass in Mars-sized embryos and only a small fraction of the total disc mass in the planetesimal population. From this, we infer that the Moon-forming event occurred between approximately 60 and approximately 130 Myr after the formation of the first solids and was caused most likely by an object with a mass similar to that of Mars.

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4128261PMC
http://dx.doi.org/10.1098/rsta.2013.0174DOI Listing

Publication Analysis

Top Keywords

giant impact
12
impact phase
12
total mass
12
mass
11
terrestrial planet
8
planet formation
8
grand tack
8
terrestrial planets
8
embryos planetesimals
8
mass planetesimal
8

Similar Publications

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!