Le 30 janvier 2015
De 10h30 à 12h00
Mohamad Ali-Dib
Observatoire de Besançon
The properties and chemical compositions of giant planets strongly depend on their formation
locations. The formation mechanisms of the ice giants Uranus and Neptune, and their
elemental and isotopic compositions, have long been debated. The density of solids in the
outer protosolar nebula is too low to explain their formation within a timescale consistent
with the presence of the gaseous protoplanetary disk , and spectroscopic observations show
that both planets are highly enriched in carbon, very poor in nitrogen, and the ices
from which they originally formed might had deuterium-to-hydrogen ratios lower than the
predicted cometary value, unexplained properties observed in no other planets. Here we
show that all these properties can be explained naturally if Uranus and Neptune both formed
at the carbon monoxide iceline location, namely the region where this gas condensates in
the protosolar nebula. We additionally show how this same model can explain the C/O ratio
measured in some exoplanets mainly WASP 12b.
References:
Ali-Dib, M. et al. ApJ, Volume 793, Issue 1, article id. 9, 7 pp. (2014).
Ali-Dib, M. et al. ApJ. Volume 785, Issue 2, article id. 125, 7 pp. (2014).