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Newly discovered planet Kepler 78b orbits its star every 8.5 hours

August 19, 2013|By Eryn Brown
  • The field of view of NASA's Kepler Space Telescope.
The field of view of NASA's Kepler Space Telescope. (Carter Roberts / NASA )

Astronomers have discovered a planet that circles its star once every 8.5 hours, giving it one of the shortest orbital periods ever seen.

It's an exciting find, but not for the usual reasons. Much of the search for exoplanets focuses on seeking out Earth-like worlds that can maintain liquid water on their surface -- and thus, the thinking goes, possibly harbor life. 

Kepler 78b, as the new planet has been named, is not such a place. The researchers who reported its discovery, based at MIT and other universities, said in a statement Monday that the small planet is about 40 times closer to its star than Mercury is to the sun and that temperatures on its surface could reach more than 5,000 degrees Fahrenheit. Kepler 78b is likely to be covered with an ocean of molten rock.

“You’d have to really stretch your imagination to imagine living on a lava world,” said MIT astrophysicist Josh Winn, who co-wrote a paper about the distant planet in the Astrophysical Journal. 

But even though Kepler 78b wouldn’t be a fun place to visit, its discovery is valuable to scientists because its tight orbit may allow measurement of its gravitational influence on its star, and therefore its mass -- which would make it the first Earth-sized exoplanet whose mass is known. 

What’s more, team members were able to detect light coming from Kepler 78b: another first for a planet so small. The light may come from radiation on the planet’s boiling surface, or it may be reflected light.  Either way, researchers will be able to analyze the components of the light to learn more about Kepler 78b’s atmosphere, the team said.

Winn and his colleagues found Kepler 78b by developing new techniques to analyze data collected by the Kepler Space Telescope. Though the telescope has been hobbled since the spring and is no longer continuing its search for unseen exoplanets, scientists are still sifting through light curves the telescope collected over about four years of operation.  

Last week, NASA astrophysics director Paul Hertz said he thought "the best was yet to come" for Kepler, and that measurements collected by the craft would continue revealing discoveries for years.

For his part, MIT’s Winn said that he hoped to find more close-orbiting exoplanets as well -- perhaps around cold brown dwarf stars. Such planets “would still be habitable, at the right temperature,” he added.

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