Exo-Planet Discovered With Chemistry Vastly Different than Earth --A Surface of Graphite and Diamond

 

          

 

New research led by Yale University scientists suggests that a rocky planet twice Earth's size orbiting a nearby star is a diamond planet. "This is our first glimpse of a rocky world with a fundamentally different chemistry from Earth," said lead researcher 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." The study estimates that at least a third of the planet's mass—the equivalent of about three Earth masses—could be diamond.

"By contrast, Earth's interior is rich in oxygen, but extremely poor in carbon—less than a part in thousand by mass," says co-author and Yale geophysicist Kanani Lee. The identification of a carbon-rich super-Earth means that distant rocky planets can no longer be assumed to have chemical constituents, interiors, atmospheres, or biologies similar to those of Earth.

The paper reporting the findings has been accepted for publication in the journal Astrophysical Journal Letters. The planet—called 55 Cancri e—has a radius twice Earth's, and a mass eight times greater, making it a "super-Earth." It is one of five planets orbiting a sun-like star, 55 Cancri, that is located 40 light years from Earth yet visible to the naked eye in the constellation of Cancer.

The planet orbits at hyper speed—its year lasts just 18 hours, in contrast to Earth's 365 days. It is also blazingly hot, with a temperature of about 3,900 degrees Fahrenheit, researchers said, a far cry from a habitable world. The planet was first observed transiting its star last year, allowing astronomers to measure its radius for the first time. This new information, combined with the most recent estimate of its mass, allowed Madhusudhan and colleagues to infer its chemical composition using models of its interior and computing all possible combinations of elements and compounds that would yield those specific characteristics.

Astronomers had previously reported that the host star has more carbon than oxygen, and Madhusudhan and colleagues confirmed that substantial amounts of carbon and silicon carbide, and a negligible amount of water ice, were available during the planet's formation. Astronomers also thought 55 Cancri e contained a substantial amount of super-heated water, based on the assumption that its chemical makeup was similar to Earth's, Madhusudhan said. But the new research suggests 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.

The discovery also opens new avenues for the study of geochemistry and geophysical processes in Earth-sized alien planets. A carbon-rich composition could influence the planet's thermal evolution and plate tectonics, for example, with implications for volcanism, seismic activity, and mountain formation. "Stars are simple—given a star's mass and age, you know its basic structure and history," said David Spergel, professor of astronomy and chair of astrophysical sciences at Princeton University, who is not a co-author of the study. "Planets are much more complex.

This 'diamond-rich super-Earth' is likely just one example of the rich sets of discoveries that await us as we begin to explore planets around nearby stars." In 2011, Madhusudhan led the first discovery of a carbon-rich atmosphere in a distant gas giant planet, opening the possibility of long-theorized carbon-rich rocky planets (or "diamond planets").

The new research represents the first time that astronomers have identified a likely diamond planet around a sun-like star and specified its chemical make-up. Follow-up observations of the planet's atmosphere and additional estimates of the stellar composition would strengthen the findings about the planet's chemical composition.

For more information: "A Possible Carbon-rich Interior in Super-Earth 55 Cancri e," Astrophysical Journal Letters. Journal reference: Astrophysical Journal Letters

The Daily Galaxy via Yale University

Image credit: NASA

Comments

[pAYNER]

Diamond planets you say, please don't tell my wife!!!

[Harry R Ray]

What makes this PARTICULARLY wierd is that we now have THREE totally different models for this planet! One is from Spitzer data supporting an envelope of supercritical water but no(VERY STRANGE)appreciable transfer of heat from the dayside to the nightside of the planet. Another is from a ground-based telescope called "ACME", which favors an 80%hydrocen to 20%water vapor atmosphere with a MUCH LOWER(ALSO VERY STRANGE, because if this is true, Spitzer should NOT have detected the secondary eclipse)dayside temperature and very efficient transport pf heat to the nightside. This new model would eliminate the two above mentioned "VERY STRANGE"'s. ALSO, a very suprising detection of possible atmospheric leakage from the next planet out, 55Cancri b may indicate that it is NOT a gas giant, as theorized, but, instead, a carbon based HYPER-EARTH with a radius similar to Neptune, and a very thin hydrogen atmosphere that is escaping into space, NOT due to stellar radiation from 55Cancri, but, instead, due to extreme heat leaking out of the planet's interior.

[Levi Anderson]

Its amazing that there can be planets so different from ours, and then there's the fact that so much of it is made up of materials that are considered "precious" on earth. I think there is definatly something to interplanetary mining (though thats probably a long way off).

P.S. The "chair of astrophysical sciences" used to be called Director of the Universe. Did it not?

[Harry R Ray]

SORRY! I meant to type "of" instead of "pf".

[katesisco]

"--due to extreme heat leaking from the planet's surface."
I theorize that this condition is not uncommon and is not due to internal formation heat but from outside influences heating the core. How this happens I do not propose to know.

[Bigfan]

Finally, a diamond bigger than Kim Kardashians engagement ring!

[Daniel Fabricius]

that should bring down the value of diamonds hehe

[John]

Could it be a shell of carbon/diamond? After all, the analysis is based on reflected light, not density.

What benefit could a dyson-type structure have around a planet?

[jaime]

There will come a time when we are nomads living off the minerals of the systems we inhabit – or die before we get that far