[LINK] "Meet 55 Cancri e, the Planet Made of Diamonds"

[rfmcdonald]

The etymology of the name of exoplanet 55 Cancri e is simple: it was the fourth planet discovered to be orbiting the incidentally Sun-like star 55 Cancri A, forty light-years away. 55 Cancri e turns out to be important, as Universe Today's Jason Major notes, as the prototype of a diamond planet.

(Pulsar PSR J1719-1438, as I noted last August, also has a diamond planet, but that world is likely to have started off as a star baked by the supernova explosion that created the pulsar.)

55 Cancri e — an exoplanet discovered in 2004 — is more than twice Earth’s diameter and over eight times more massive, making it a so-called “super Earth.” Earlier this year it made headlines by being the first Earth-sized exoplanet whose light was directly observed via the infrared capabilities of NASA’s Spitzer Space Telescope.

Using information about 55 Cancri e’s size, mass and orbital velocity, as well as the composition of its parent star 55 Cancri (located 40 light years away in the constellation Cancer) a research team led by scientists from Yale University created computer models to determine what the planet is most likely made of.

They determined that 55 Cancri e is composed primarily of carbon (as graphite and diamond), iron, silicon carbide, and possibly some silicates. The researchers estimate that at least a third of the planet’s mass — the equivalent of about three Earth masses — could be diamond.

“This is our first glimpse of a rocky world with a fundamentally different chemistry from Earth. The surface of this planet is likely covered in graphite and diamond rather than water and granite.”

So what would one expect to find on a world made of diamond?

“On this planet there would basically be a thin layer below the surface which will have both graphite and diamond,” Madhusudhan told Universe Today in an email. “But, below that there will be a thick layer (a third of the radius) with mostly diamond. For a large part the diamond will be like the diamond on Earth, except really, really pure.

“But at greater depths the diamond could also be in liquid form,” Madhusudhan added.