30 November 2000 CfA Colloquium


Title: Composition of Extrasolar Giant Planets

Speaker: Tristan Guillot

Abstract: Jupiter, Saturn, Uranus and Neptune are known to be enriched in heavy elements compared to a mixture of solar composition. The ability to measure radii of giant planets orbiting other suns should yield a determination of the global amount of heavy elements present in these objects. This information would be extremely valuable for validating and constraining models of planet formation.

However, I will show that this goal requires a detail modeling of the evolution, and therefore of the atmospheric structure of these objects. A class of extrasolar giant planets is particularly interesting in that respect: ``hot Jupiters'' represent about 40% of the extrasolar planets discovered so far and have the highest probability of being detected in transit in front of their star. I will show that in these planets, expected to be in synchronous rotation with their star, zonal winds are most likely incapable of efficiently redistributing heat from the day side to the night side, hence questionning the validity of attempts to model their atmospheric structures with a mean stellar insolation.

Reference for students:

Lunch with the students will be on Friday, December 1st at 12:00 in A-101.