NASA's Kepler Mission K2 team announced the discovery of another new world today, two months after the Kepler spacecraft ran out of fuel on October 30th, and ended its mission after nine years, during which it discovered 2,600 confirmed planets around other stars - the bulk of those now known - along with thousands of additional candidates astronomers are working to confirm.
A year ago at the American Astronomical Society meeting, it was announced that citizen scientists helped discover five planets between the size of Earth and Neptune around star K2-138, the first multiplanet system found through crowdsourcing. At a cool 300 degrees Fahrenheit (~149 degrees Celsius), it's also "relatively cool" for a planet orbiting so close to its star.
"It's the coolest small planet that we know of around a star this bright", Diana Dragomir, a postdoc in MIT Kavli Institute who led this latest discovery, said in a statement. "We know a lot about atmospheres of hot planets, but because it's very hard to find small planets that orbit farther from their stars, and are therefore cooler, we haven't been able to learn much about these smaller, cooler planets".More news: Technics relaunches legendary DJ turntable with SL-1200 MK7
"We think this planet wouldn't be as gaseous as Neptune or Uranus, which are mostly hydrogen and really puffy", Dragomir said.
Few planets that orbit close to their stars are more than 1.5 times as large as Earth, yet K2-288Bb is estimated to be roughly 1.9 times the size of our planet. It has also discovered a super-Earth and a rocky world, making three exoplanet discoveries in the first three months since it began surveying the sky in July.
The new world, known as K2-288Bb, could be rocky or could be a gas-rich planet similar to Neptune. "The planet likely has a density of water, or a thick atmosphere".
"It's a very exciting discovery due to how it was found, its temperate orbit and because planets of this size seem to be relatively uncommon", said Adina Feinstein, University of Chicago graduate student and lead author of the paper on the discovery, published by the Astronomical Journal. The satellite will cover virtually the entire sky by the end of its two-year prime mission. The exoplanet lies in the stellar system K2-288, which has two dim, cool stars. They had noticed the same system and its two transits. Dr. Ricker briefly touched on a potential extended mission for the planet-hunting telescope that would begin in 2020 and carry on until 2022, in which it would look at additional sectors of the sky that were missed during its first years of operation.
As it turned out, though, the team wasn't actually analyzing all of the data.More news: Great win but India rue the ones that got away
"Because there was an interruption in data around that time, we initially didn't see a second transit, and were pretty disappointed", Dragomir recalls.
"There was quite some detective work involved, and the right people were there at the right time", Dragomir says.
They also used data from the Planet Finder Spectrograph, an instrument installed on the Magellan Telescope in Chile, to further validate their findings and constrain the planet's mass and orbit. "But we were lucky and we caught the signals, and they were really clear".
So the reprocessed, "cleaned-up" light curves were uploaded through the Exoplanet Explorers project on online platform Zooniverse, and the public was invited to "go forth and find us planets", Feinstein said.
Feinstein and Makennah Bristow, an undergraduate student at the University of North Carolina Asheville, worked as interns at NASA's Goddard Space Flight Center, searching the data for transits.More news: US House committee queries airport staffing during shutdown