HR: 16:30h
AN: P54A-03    [Abstracts]
TI: Evolution of Super-Earths
AU: * Valencia, D
EM: valencia@mail.geophysics.harvard.edu
AF: Earth and Planetary Sciences Harvard University, 20 Oxford Street, Cambridge, MA 02138, United States
AU: O'Connell, R J
EM: oconnell@geophysics.harvard.edu
AF: Earth and Planetary Sciences Harvard University, 20 Oxford Street, Cambridge, MA 02138, United States
AU: Sasselov, D D
EM: dsasselov@cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, United States
AB: Super-Earths are the newest class of planets discovered with masses in the 1-10 M_\oplus range. Determining their physical properties is of interest to better design detection projects and to further our understanding of Earth. Additionally, among them we might find true Earth analogs. To understand their physical properties it is crucial to understand their structure and evolution. We model the evolution of super-Earths from their hot initial state of magma ocean convection to the transition into plate tectonics and eventually stagnant lid. The timescales between the different states depend on the mass of the planet which determines the size, density, gravity, heat flow and therefore, the Rayleigh number. The magma ocean state is the most favorable for direct detection (TPF, Darwin) because of the high surface temperatures due to large mantle convective transport and the presence of a thick atmosphere. The transition to plate tectonics is possible due to the large convective stresses underneath thin lithospheric plates, with both being a result of large Rayleigh numbers. For a given planetary mass there is a threshold heat flow limit below which the convective stresses are not enough to overcome the plate's resistance to deformation and plate tectonics is unlikely to occur. Super-Earths above this threshold are likely to exhibit plate tectonics and therefore are good candidates in the search of habitable planets.
DE: 5215 Origin of life
DE: 5410 Composition (1060, 3672)
DE: 5430 Interiors (8147)
DE: 5455 Origin and evolution
DE: 5475 Tectonics (8149)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting