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Séminaire : The chemical diversity of extraterrestrial worlds

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Jeudi 15 novembre 2012 à 14h00

Salle de conférence de l’observatoire

par Nikku Madhusudhan (Yale University)

Résumé :

Recent advances in observations of extrasolar planets are leading to
unprecedented constraints on chemical compositions of their atmospheres and interiors. In this talk, I will present our recent finding of a possible diamond-rich interior in super-Earth 55 Cancri e, a planet with twice Earth’s size and eight times Earth’s mass. Terrestrial planets in the solar system, such as the Earth, are oxygen-rich, with silicates and iron being the most common minerals in their interiors. However, the true chemical diversity of rocky planets orbiting other stars is yet unknown. We find that the sum-total of available data of 55 Cancri e, including its mass and radius, and the stellar abundances, support the possibility of a carbon-rich composition in its interior - with carbon (as graphite and diamond), iron, silicon carbide, and/or silicates as the primary constituents. The possibility of a C-rich interior in 55 Cancri e opens a new regime of geochemistry and geophysics in extraterrestrial rocky planets, compared to terrestrial planets in the solar system. Besides 55
Cancri e, I will also discuss emerging constraints on the chemical
compositions of a wide range of other extrasolar planets - from
super-Earths and exo-Neptunes to giant gaseous exoplanets - and their implications for our understanding of chemical diversity in
extraterrestrial worlds.