Physics
Scientific paper
Oct 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011epsc.conf.1121v&link_type=abstract
EPSC-DPS Joint Meeting 2011, held 2-7 October 2011 in Nantes, France. http://meetings.copernicus.org/epsc-dps2011, p.1121
Physics
Scientific paper
In the past decade there has been an explosion in the number of exoplanets that have been discovered. These newly discovered planets have proven to be extraordinarily diverse in their physical characteristics. This has allowed planetary scientists to explore examples of planets beyond the small sample size of our solar system. Of particular interest to interior modellers is the class of planets known as "super-Earths", defined as solid exoplanets with a mass greater than one Earth mass, without a significant gas envelope [1]. Inside these planets exist temperatures and pressures which are far greater than those found within the solid planets of our solar system. With these extreme conditions comes the possibility of exotic material properties, which could affect the internal dynamics and evolution of the planet. Recent theoretical work has predicted the dissociation of MgSiO3 at the conditions of the core mantle boundaries of larger super-Earths ( 8Me, where Me is the mass of the Earth) [2],[3]. These dissociated silicates should conduct electricity with a conductivity comparable to that of liquid iron [4]. Since MgSiO3 is likely a major constituent of the mantles of any terrestrial exoplanet, we should expect the lower mantles of large super-Earths to be electrically conductive. A conductive lower mantle should have an effect on any dynamo generated magnetic field in two ways. First, since magnetic fields freeze into conductive materials, an electrically conducting lower mantle can impart a Lorentz force to the fluid part of the core. This will affect the internal dynamics of the dynamo by changing the force balance. Secondly, any time varying components of the planetary magnetic field will be severely attenuated by the conducting mantle. This is because of a screening effect that conductors have on time varying electrical or magnetic fields. In this paper we use a numerical dynamo model with a surrounding conducting shell to consider both of these effects.
Elkins-Tanton Linda
Stanley Sabine
Vilim Ryan
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