When
3:30 p.m., April 1, 2008
Where
Kuiper Space Sciences Building 308
Dr. Christophe Sotin, of the Jet Propulsion Laboratory, is the scheduled speaker.
Abstract:
By comparison with the Earth-like planets and the large icy satellites of the Solar System, one can model the internal structure of extrasolar planets. The input parameters are the composition of the star (Fe/Si and Mg/Si), the Mg content of the mantle (Mg# = Mg/[Mg+Fe]), the amount of H2O and the total mass of the planet. Equations of State of the different materials that are likely to be present within such planets have been obtained thanks to recent progress in high-pressure experiments. They are used to compute the planetary radius as a function of the total mass. Based on accretion models and data on planetary differentiation, the internal structure is likely to consist of an iron-rich core, a silicate mantle and an outer silicate crust resulting from magma formation in the mantle. The amount of H2O and the surface temperature control the possibility for these planets to harbor an ocean.
In addition to discussing the assumptions made in this kind of modeling and to providing the scaling laws between radius and mass, this talk will address the controversial question of plate tectonics on Super-Earths. Two papers (Valencia et al., 2007, O'Neill and Lenardic, 2007) came out at the same time with opposite conclusions. Plate tectonics is an important process that recycles volatiles into the mantle and provides a time scale of hundreds of millions of years for the cycle of elements required for the development of life. Our knowledge of the relationships between thermal convection and plate tectonics on terrestrial planets of the solar system is used to assess what we can expect on super-sized Earths.
Abstract:
By comparison with the Earth-like planets and the large icy satellites of the Solar System, one can model the internal structure of extrasolar planets. The input parameters are the composition of the star (Fe/Si and Mg/Si), the Mg content of the mantle (Mg# = Mg/[Mg+Fe]), the amount of H2O and the total mass of the planet. Equations of State of the different materials that are likely to be present within such planets have been obtained thanks to recent progress in high-pressure experiments. They are used to compute the planetary radius as a function of the total mass. Based on accretion models and data on planetary differentiation, the internal structure is likely to consist of an iron-rich core, a silicate mantle and an outer silicate crust resulting from magma formation in the mantle. The amount of H2O and the surface temperature control the possibility for these planets to harbor an ocean.
In addition to discussing the assumptions made in this kind of modeling and to providing the scaling laws between radius and mass, this talk will address the controversial question of plate tectonics on Super-Earths. Two papers (Valencia et al., 2007, O'Neill and Lenardic, 2007) came out at the same time with opposite conclusions. Plate tectonics is an important process that recycles volatiles into the mantle and provides a time scale of hundreds of millions of years for the cycle of elements required for the development of life. Our knowledge of the relationships between thermal convection and plate tectonics on terrestrial planets of the solar system is used to assess what we can expect on super-sized Earths.
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