The detection of planet K2-288Bb, which orbits one of the stars in a binary system located 226 light-years from Earth, took advantage of archived Kepler data as well as the sharp eyes of citizen scientists participating in the Exoplanet Explorers program.
Scientists have used data from NASA's Kepler space telescope to discover a new planet that is twice as large as Earth. The team, however, needed at least three transits to claim the discovery of a candidate planet and they did not find a third signal in the observations they reviewed.
"It's the coolest small planet that we know of around a star this bright", Dr Dragomir said.
The new planet's surface reaches about 300℉, which, according to the MIT Kavli Institute for Astrophysics and Space Research, is "relatively cool", considering the proximity to its star, which is nearly as bright as our Sun. "If confirmed, it will be the smallest planet we have found to date", study co-author Chelsea Huang, a colleague of Dragomir's at the MIT Kavli Institute, said today during a briefing at the American Astronomical Society's winter meeting in Seattle.
Calling the planet small is a bit misleading, the team says that HD 21749b is about three times the size of Earth placing it into the sub-Neptune category.
K2-288Bb is half the size of Neptune or 1.9 times the size of Earth, placing it in the "Fulton gap " between 1.5 and two times the size of Earth.
But it is unlikely that the planet is rocky and therefore habitable; it's more likely made of gas, of a kind that is much more dense than the atmospheres of either Neptune or Uranus. It could be a water planet or have some other type of substantial atmosphere, ' explained Diana Dragomir, a Hubble Fellow at MKI and lead author of apaper on the planet's discovery.
On the bright side, there is evidence of a second, still unconfirmed planet in the same system, this one with a much shorter 7.8-day orbit.
NASA's newest planet-hunting probe has bagged another alien world, the eighth confirmed find for the young mission. That is, it looks for tiny dips in starlight caused when planets cross their host stars' faces from the satellite's perspective. "NASA's Kepler space telescope caught six of these events as they brightened during its first four years of operations". Indeed, HD 21749b is very far-flung for TESS; two other smallish worlds found by the mission have orbital periods of 11 hours and 6.3 days, respectively. Observing just one sector of the sky once it began science operations, researchers announced at AAS that TESS has already identified six supernovae - a remarkable finding.
These findings are from just the first few sectors TESS has observed in the Southern Hemispheres, beginning in July.
Its size is unusual for an exoplanet (the term for a planet that orbits a star outside our solar system). Those planets could be the best candidates for supporting life outside our solar system.
Kepler was missing the data due to slight changes when it was repositioned in space.
Follow-up observations were made with multiple telescopes to confirm the exoplanet.