Scientists find first carbon-rich planet

Diamonds and graphite as big as earthly rocks may be strewn around there

House of Diamonds: The newly-found WASP-12b.

Located at a distance of 1200 light years from the earth, the new planet, called WASP-12b, orbits a star slightly hotter than the Sun. As big as Jupiter, it is outside the solar system and different from all known planets.

Planets generally have water, dust and oxygen. But not WASP-12, which is the first planet whose atmosphere is highly rich in carbon.

“It shows something else is going on in planet formation, opening up a new area for planet formation processes,” said Nikku Madhusudhan from Massachusetts Institute of Technology (MIT), principal investigator of the study.

A diamond mine

WASP-12 is full of gas without any surface. But its discovery suggests there might be smaller rocky carbon-rich planets whose rocks are nothing but diamond and graphite.
“If high carbon-oxygen ratios are common, then the formation processes and compositions of extrasolar planets are probably very different,” Madhusudhan and colleagues from other USA and UK reported in “Nature.”

The planet orbits the star at a distance 40 times closer than the Earth is to the Sun — making WASP-12b one of the hottest known exoplanets, with a surface temperature exceeding 2,200 degrees Celsius.

“Due to a high carbon-oxygen ratio, the planet’s internal chemistry would be different, suggesting the rocks in it may be diamonds and graphite,” Madhusudhan, a former Bangalorean who did his PhD from Banaras Hindu University told Deccan Herald.


The planet was found last year by UK Wide-Angle Search for Planets using the WASP telescope in La Palma. Madhusudhan and his colleagues have now observed WASP-12b with NASA’s Spitzer Space Telescope to unearth more details.

“A rocky planet in such a planetary system could have an interior abundant in diamonds and a surface littered with graphite and diamonds,” said Joe Harrington, of the University of Central Florida, who led the analysis of the Spitzer data.

WASP-12’s atmosphere could be poisonous to humans. “But there could be a different form of life that thrives on carbon,” argued Madhusudhan.

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