First Transiting Planets in a Star Cluster Discovered

Posted on June 26, 2013

Kepler-66b and Kepler-67b in NGC 6811


3,000 light-years from Earth, in the star cluster NGC 6811, astronomers have found two planets - Kepler-66b and Kepler-67b - smaller than Neptune orbiting Sun-like stars. The discovery, published in the journal Nature, shows planets can develop even in crowded clusters jam-packed with stars. The planets were found using data from NASA's Kepler spacecraft, which hunts for planets that transit, or cross in front of, their host stars. These are the first transiting planets discovered in a star cluster.

Lead author Soren Meibom of the Harvard-Smithsonian Center for Astrophysics (CfA), said in a release, "Old clusters represent a stellar environment much different than the birthplace of the Sun and other planet-hosting field stars. And we thought maybe planets couldn't easily form and survive in the stressful environments of dense clusters, in part because for a long time we couldn't find them."

Meibom and his colleagues have measured the age of NGC 6811 to be one billion years. Kepler-66b and Kepler-67b join a small group of planets discovered so far that have precisely determined ages, distances, and sizes.

Meibom says, "These planets are cosmic extremophiles. Finding them shows that small planets can form and survive for at least a billion years, even in a chaotic and hostile environment."

Image: Michael Bachofner