Rocky exoplanets' cores - Iron alloys under extreme conditions

Among different materials, properties of iron and iron alloys under extreme conditions are one of the most important challenges.

In Earth-like planets, differences in bulk masses will translate into different P-T conditions at the centre of these bodies and reflects on the solid versus liquid nature of the core and on the stable crystalline structure of the solid phase.

Calculations of the iron melting curve at multi-megabar pressures predict that planets twice the mass of Earth should have entirely solid cores, with strong implications for the possible existence of a magnetic field (Morard, 2011).

© D.D. Sasselov

Nature 451, 29-31(3 January 2008)

Two possible varieties for super-earth planets :

a: rocky

b: ocean