Earth-sized planet found hiding around Sun-like star
The pair are the closest match to the Sun and Earth yet detected
A distant
star and its planet, which bear a close resemblance to our own Sun and Earth, have recently been discovered.
The planetary system was found in data from the exoplanet-hunting Kepler Space Telescope, which looked for dips in brightness caused by planets transiting across their stars’ discs. This photometric transit method favours the detection of Earth-sized planets around dim, red dwarf stars rather than around those like our Sun. Red dwarfs are relatively cool, however, and emit high-energy solar flares, characteristics which could render such planets more hostile to life.
But Kepler-160, the host star of this newly discovered planet, is only slightly larger than our Sun and has a temperature of 5,200˚C – only 300˚C cooler. Astronomers already knew the star had two Neptune-sized planets from an initial analysis of the Kepler data, but there were fluctuations in their timing that suggested another planet might be present in the star’s planetary system.
A team from the Max Planck Institute for Solar System Research (MPS) went back over the data using a new technique to tease out the subtle signs of two smaller planets moving around the star.
“Our analysis suggests that Kepler-160 is orbited by a total of four planets and not by two,” says René Heller from MPS, who led the team.
One of the two new stars could only be detected indirectly, but the other,
KOI-456.04, is 1.9 times the radius of Earth and orbits its star once every 378 days – just 13 days longer than an Earth year.
“Our improvement is important in the search for small, Earth-sized planets,” says Heller. “The planetary signal is so faint that it’s almost hidden in the noise of the data.”
It’s Sun-like host star means the light falling on the planet will be very similar to our own sunshine, rather than the infrared-laden light of a red dwarf.
“KOI-456.04 is relatively large compared to many other planets that are considered potentially habitable. However, it’s the combination of its size, at less than double that of Earth, and its solar-type host star that makes it so special and familiar,” says Heller.