Exoplanets: I’ll Stop the World and Melt With You

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Source:  Caleb A. Scharf, Scientific American
Excerpt: Gas giant planets are among the most beautiful and awe-inspiring worlds. …The major bulk of these planets, and their cousins around other stars, consists of primordial hydrogen and helium – vast envelopes of matter cocooning their cores and rendering them inaccessible to us. The pressures deep down in a planet like Jupiter can reach a hundred million times those on Earth’s surface, and temperatures can be tens of thousands of Kelvin. …At such huge pressures, hydrogen becomes a liquid, even though temperatures are high. …A new paper showed up this past week by Wilson and Militzer that suggests … if a gas giant planet forms around a large rocky proto-planet (perhaps 10 times the mass of the Earth), the liquid metallic hydrogen that eventually envelops that core may also melt, or dissolve it. ... bigger, hotter “super-Jupiter” exoplanets may appear more abundant in heavy elements to our astronomical instruments not because they’re getting polluted by in-falling stuff, but because they’ve digested their original cores.

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