Magma Ocean Lifetimes
Abstract
The early evolution of a terrestrial planet may play an important role in its subsequent thermal evolution. Terrestrial super-Earths are expected to evolve similarly to terrestrial planets: quickly cooling from a magma ocean state, in which they experience high surface heat fluxes and temperatures. We study the solidification of magma oceans in terrestrial super-Earths and determine how long this phase lasts in the presence and absence of an atmosphere (grey and water-vapor). In the blackbody approximation the timescales are of order 105 years, while in a grey approximation the timescales can be extended to a few million years for an optically thick atmosphere (τ =100). We find that a 10 earth-mass planet takes about twice as long to cool as a one earth-mass planet. This early epoch is the most amenable to direct observation due to the high planetary heat flux; depending on how long it lasts it might be possible to directly detect super-Earths in this hot state. Development of more sophisticated atmospheric models may allow the inference of outgassing products from spectral signatures.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.P13C1329V
- Keywords:
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- 5225 Early environment of Earth;
- 5430 Interiors (8147);
- 6296 Extra-solar planets;
- 8145 Physics of magma and magma bodies