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Diamond 'super-Earth' may not be quite as precious

An alien world thought to be the first known planet to consist largely of diamond appears less likely to be of such precious nature.

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A planet 40 light years from our solar system, believed to be the first-ever discovered planet to consist largely of diamond, may in fact be of less exquisite nature, according to new research led by University of Arizona astronomy graduate student Johanna Teske.

Revisiting public data from previous telescope observations, Teske's team analyzed the available data in more detail and concluded that carbon – the chemical element diamonds are made of – appears to be less abundant in relation to oxygen in the planet's host star – and by extension, perhaps the planet – than was suggested by a study of the host star published in 2010.

"The 2010 paper found that '55 Cancri,' a star that hosts five planets, has a carbon-to-oxygen ratio greater than one," Teske said. "This observation helped motivate a paper last year about the innermost planet of the system, the 'super-Earth' 55 Cancri e. Using observations of the planet's mass and radius to create models of its interior that assumed the same carbon-to-oxygen ratio of the star, the 2012 paper suggested the planet contains more carbon than oxygen."

"However, our analysis makes this seem less likely because the host star doesn't appear as carbon-rich as previously thought," Teske said.

Observations obtained in 2010, together with simulations astronomers use to model a planet's interior based on data like...

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