Harvard-Smithsonian Center for Astrophysics | 2016 Feb 08
[c][attachment=0]base[1].jpg[/attachment][/c][hr][/hr]Every school kid learns the basic structure of the Earth: a thin outer crust, a thick mantle, and a Mars-sized core. But is this structure universal? Will rocky exoplanets orbiting other stars have the same three layers? New research suggests that the answer is yes - they will have interiors very similar to Earth.
"We wanted to see how Earth-like these rocky planets are. It turns out they are very Earth-like," says lead author Li Zeng of the Harvard-Smithsonian Center for Astrophysics (CfA).
To reach this conclusion Zeng and his co-authors applied a computer model known as the Preliminary Reference Earth Model (PREM), which is the standard model for Earth's interior. They adjusted it to accommodate different masses and compositions, and applied it to six known rocky exoplanets with well-measured masses and physical sizes.
They found that the other planets, despite their differences from Earth, all should have a nickel/iron core containing about 30 percent of the planet's mass. In comparison, about a third of the Earth's mass is in its core. The remainder of each planet would be mantle and crust, just as with Earth. ...
Mass-Radius Relation for Rocky Planets based on PREM - Li Zeng, Dimitar Sasselov, Stein Jacobsen
- arXiv.org > astro-ph > arXiv:1512.08827 > 30 Dec 2015 (v1), 04 Feb 2016 (v2)