The discovery of Kepler-10c was presented June 2nd at the 224th American Astronomical Society meeting.
Dubbed a “mega-Earth,” the exoplanet Kepler-10c weighs 17 times as much as Earth and it circles a sunlike star in the constellation Draco.
The mega-Earth orbits its parent star once every 45 days. Kepler-10c is probably too close to its star to be hospitable to life, and it isn’t the only orbiting the yellow star. Kepler-10 also plays host to a “lava world” called Kepler-10b that is three times the mass of Earth and speeds around its star in a 20-hour orbit.
NASA’s Kepler space telescope first spotted Kepler-10c, however, the exoplanet-hunting tool is not able to tell whether an alien world it finds is gaseous or rocky. The new planet’s size initially signaled that it fell into the “mini-Neptune” category, meaning it would have a thick envelope of gas covering the planet.
CfA astronomer Xavier Dumusque and his team used the HARPS-North instrument on the Telescopio Nazionale Galileo in the Canary Islands to measure Kepler-10c’s mass. They found that the planet is, in fact, rocky and not a mini-Neptune.
“Kepler-10c didn’t lose its atmosphere over time. It’s massive enough to have held onto one if it ever had it,” Dumusque said in a statement. “It must have formed the way we see it now.”
Scientists think the Kepler-10c system is actually quite old, forming less than 3 billion years after the Big Bang. The system’s early formation suggests that, although the materials were scarce, there were enough heavy elements like silicon and iron to form rocky worlds relatively early on in the history of the universe, according to the CfA.
“Finding Kepler-10c tells us that rocky planets could form much earlier than we thought,” Sasselov said in a statement. “And if you can make rocks, you can make life.”
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