Exoplanet HIP 116454b has been discovered by the Kepler spacecraft, marking the first alien world discovered by the once-defunct observatory during the second phase of its mission.
Kepler was launched into space in 2009, finding evidence for hundreds of new planets in just a few years. The observatory carefully measures light coming from stars, recording when light dims as a planet orbits in front of the stellar body, as seen from Earth. In May 2013, the second of four reaction wheels failed, making it impossible to accurately position the spacecraft for observations. Scientists at NASA devised a new plan, to use pressure from solar wind to help align the vehicle. This became known as the K2 mission. Advanced algorithms allow astronomers to compensate for slight drifting of the spacecraft during observations.
During the second half of its mission, Kepler will continue its search for alien worlds, as well as studying far-distant galaxies and star clusters.
The star HIP 116454, around which the newly-discovered world orbits, lies roughly 180 light years away from our own family of planets. Because the star is fairly close to the Sun, and relatively bright as seen from Earth, astronomers are likely to carry out additional surveys of the system in the near future.
"HIP 116454b will be a top target for telescopes on the ground and in space," John Johnson from the Harvard-Smithsonian Center for Astrophysics (CfA), said.
Kepler started tests of the new K2 mission in February 2014. It was during this first run that Kepler recorded data from HIP 116454, revealing evidence of the alien world. Analysis of the observations show the newly-discovered planet is around 2.5 times as large as the Earth, and 12 times as massive. This super-Earth is likely either a mini-Neptune, with an extensive atmosphere, or rich with water. The star around which this planet orbits is classified as a type K orange dwarf - significantly smaller and cooler than our own Sun. Despite this, the 8.4 million mile distance between the super-Earth and the star likely make the planet far too hot to support life as we know it.
"The Kepler mission showed us that planets larger in size than Earth and smaller than Neptune are common in the galaxy, yet they are absent in our solar system. K2 is uniquely positioned to dramatically refine our understanding of these alien worlds and further define the boundary between rocky worlds like Earth and ice giants like Neptune," Steve Howell, Kepler/K2 project scientist at NASA's Ames Research Center, said.
Discovery of HIP 116454b was detailed in a scientific article, accepted for publication in The Astrophysical Journal.