By Nadia Drake
When the Kepler spacecraft finds a giant planet closely orbiting a star, there’s a one in three chance that it’s not really a planet at all.
At least, that’s the case according to a new study that put some of Kepler’s thousands of candidate planets to the test using a complementary method for discovering celestial objects in stellar orbits. The results, posted June 5 on arXiv.org, suggest that 35 percent of candidate giants snuggled close to bright stars are impostors, known in the planet-hunting business as false-positives.
“Estimating the Kepler false-positive rate is one of the most burning questions in this field,” says astronomer Jean-Michel Désert of the Harvard-Smithsonian Center for Astrophysics, who has performed similar calculations for smaller planets.
Estimates by Désert and others place the false-positive rate at less than 10 percent, which isn’t necessarily contradictory given the different target populations of various research efforts.