Mega | by Brian Koberlein

NASA/Ames/JPL-Caltech/T. Pyle

A brilliant-Earth is an exoplanet that’s rocky like Earth and different terrestrial planets, however extra huge. Usually they’re round 5 – 10 Earth plenty. Something way more huge than that, so it was thought, could be huge sufficient to carry a thick ambiance, and would seemingly be a small fuel big. Uranus and Neptune, for instance are about 15 Earth plenty. However lately we’ve found a planet as huge as Neptune that’s decidedly rocky like Earth. It has generally been known as a mega-Earth.

Dumusque, et al

This specific planet is called Kepler 10c. It has been identified since 2011, however because the Kepler telescope discovers planets by the transit methodology (that means the exoplanet passes in entrance of its star) we solely knew its dimension relative to the star. On the time it was found that it was a bit greater than twice the diameter of Earth, which made it an excellent super-Earth candidate. However a current article within the Astrophysical Journal has made measurements of the Doppler movement of the mother or father star, and has measured the “wobble” of the star because of the planets orbiting it. ^{From this they decided the mass of Kepler 10c, and it was astonishingly massive. About 17 Earth plenty.}

Realizing its dimension and mass, we are able to calculated its density. This seems to be about 7 g/cc, which is larger than Earth’s 5.5 g/cc. By comparability, Neptune has the same mass, however a density of just one.6 g/cc. So Kepler 10c is clearly extra Earth-like than Neptune-like in composition.

After all the actual thriller is how such a big planet may come to be. One concept is that the mass wanted to develop into a fuel big is bigger the farther you’re from the star. ^{In line with this mannequin Kepler 10c is simply far sufficient away from its star that it may develop into huge with out reaching the crucial mass for a fuel big. After all one information level isn’t sufficient to assist a mannequin, so we’ll want to seek out extra mega-Earth’s to see if the proof actually helps it.}