Scientists Discover Diamond 'Super Earth' Planet May Not be So Precious

When scientists first discovered an alien world about 40 light-years from our solar system, they believed that it was largely made of diamond. Now, though, researchers have uncovered new evidence when it comes to the planet. It turns out that the planet is less likely to be made of diamond and is more likely to be made of something far less precious.

In order to get a better glimpse of this planet, the researchers revisited public data from previous telescope observations. They found that carbon, the chemical elements that diamonds are made of, is far less abundant in relation to oxygen in the planet's host star. By extension, it's very possible that the planet also has a lack of this carbon, which means it's very unlikely to be made of diamond.

"The 2010 paper found that '55 Cancri,' a star that hosts five planets, has a carbon-to-oxygen ratio greater than one," said Johanna Teske, one of the researchers, in a news release. "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."

Our own sun only has about half as much carbon as oxygen. This means that a star or a planet with a higher ratio between the two elements is interesting and different from what is in our own solar system. It also indicates that the planets orbiting the host star are different in composition.

So what did the scientists find about this "diamond" planet, exactly? It turns out that the world's host star contains almost 25 percent more oxygen than carbon, which is about mid-way between the Sun and what the previous study suggested. In theory, it's possible that 55 Cancri e could still have a carbon to oxygen ratio and be a diamond planet. However, the initial measurements of the planet no longer verify this fact.

"Depending on where 55 Cancri e formed in the protoplanetary disk, its carbon-to-oxygen ratio could differ from that of the host star," said Teske. "It could be higher or lower. But based on what we know at this point, 55 Cancri e is more of a 'diamond in the rough.'"

The findings are published in The Astrophysical Journal.