‘100 new planets discovered beyond our solar system’

London: Scientists have confirmed nearly 100 new planets outside our solar system, bringing the total number of exoplanets found using NASA's K2 mission to almost 300. "We started out analysing 275 candidates, of which 149 were validated as real exoplanets. In turn, 95 of these planets have proved to be new discoveries," said Andrew Mayo, doctoral student at the Technical University of Denmark.

"This research has been underway since the first K2 data release in 2014," said Mayo, main author of the research published in the Astronomical Journal. Mayo and his colleagues analysed hundreds of signals of potential exoplanets to determine which signals were created by exoplanets and which were caused by other sources. "We found that some of the signals were caused by multiple star systems or noise from the spacecraft. But we also detected planets that range from sub Earth-sized to the size of Jupiter and larger," said Mayo.

One of the planets detected was orbiting a very bright star. The Kepler spacecraft was launched in 2009 to hunt for exoplanets in a single patch of sky, but in 2013, a mechanical failure crippled the telescope. However, astronomers and engineers devised a way to repurpose and save the space telescope by changing its field of view periodically.

This solution paved the way for the follow-up K2 mission, which is still ongoing as the spacecraft searches for exoplanet transits. These transits can be found by registering dips in light caused by the shadow of an exoplanet as it crosses in front of its host star. The dips are indications of exoplanets, which must then be examined more closely in order to confirm their nature.

The first planet orbiting a star similar to our own sun was detected in 1995. Today some 3,600 exoplanets have been found, ranging from rocky Earth-sized planets to large gas giants like Jupiter. "We validated a planet on a 10-day orbit around a star called HD 212657, which is now the brightest star found by either the Kepler or K2 missions to host a validated planet. Planets around bright stars are important because astronomers can learn a lot about them from ground-based observatories," said Mayo.

"Exoplanets are a very exciting field of space science. As more planets are discovered, astronomers will develop a much better picture of the nature of exoplanets which in turn will allow us to place our own solar system into a galactic context," he said.