PARIS – Scientists from Yale University said they have identified a "diamond planet" twice the size of the Earth and eight times its mass.
The planet, named 55 Cancri e, is one of five planets orbiting a sun-like star located 40 light years from Earth in the constellation of Cancer.
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“This is our first glimpse of a rocky world with a fundamentally different chemistry from Earth,” stated Nikku Madhusudhan, a Yale postdoctoral researcher in physics and astronomy. “The surface of this planet is likely covered in graphite and diamond rather than water and granite.”
Illustration of the interior of 55 Cancri e, an extremely hot planet
with a surface of mostly graphite surrounding a thick layer of diamond,
below which is a layer of silicon-based minerals and a molten iron core
at the center. (Source Yale University)
Researchers said they observed that the planet has no water at all and appears to be composed primarily of carbon (as graphite and diamond), iron, silicon carbide, and, possibly, some silicates. At least a third of the planet's mass — the equivalent of about three Earth masses — could be diamond, they noted.
“By contrast, Earth’s interior is rich in oxygen, but extremely poor in carbon — less than a part in thousand by mass,” commented co-author and Yale geophysicist Kanani Lee.
Scientists said the identification of a carbon-rich super-Earth proves that distant rocky planets can no longer be assumed to have chemical constituents, interiors, atmospheres, or biologies similar to those of Earth.
Star map showing the planet-hosting star 55 Cancri in the constellation of Cancer. The star is visible to the naked eye. (Image by Nikku Madhusudhan. Yale University)