IGPP Seminar Series

The grand tack scenario: a new model of terrestrial planets formation

by Dr. Alessandro Morbidelli
Observatoire de la Cote d'Azur in Nice


Numerical models of the accretion process of terrestrial planets reproduce quite successfully the observed system, with one exception: the planet formed at the location of Mars is typically too massive. Hansen (2009) convincingly argue that to obtain a large Earth/Mars mass ratio, the initial distribution of the planetesimals had to be concentrated in an annulus with an outer edge at ~ 1AU. However, as admitted by Hansen himself, this assumption is totally ad-hoc; moreover it is unclear how it could be consistent with the presence of asteroids in the main belt (2-3.5 AU), which required a massive environment to form. In this talk we will present a new idea, dubbed the 'Grand Tack' scenario. This scenario is consistent with Hansen's work, reproduces reasonably well the properties of the asteroid belt in terms of orbital distribution and taxonomic-type dichotomy and is consistent with the new version of 'Nice model' (Morbidelli et al., 2007) of the orbital evolution of the giant planets of the solar system. I will discuss the implications of this new model on our understanding of the formation of the Earth (accretion timescale, origin of the accreted material) and of the origin of asteroids.
Tuesday, 05 October 2010
3853 Slichter Hall
Refreshments at 3:45 PM
Lecture at 4:00 PM