An international group of astronomers reporting in the journal Nature has discovered two extrasolar planets circling Sun-like stars in the open star cluster NGC 6811.
This image shows the newly discovered exoplanets Kepler-66b and Kepler-67b in the open star cluster NGC 6811 (Michael Bachofner)
NGC 6811 is located about 3,000 light-years away towards the constellation Cygnus.
The newly discovered alien worlds, labeled Kepler-66b and Kepler-67b, show that planets can develop in crowded clusters jam-packed with stars.
Kepler-66b and Kepler-67b are mini-Neptunes. They are about three-fourths the size of Neptune, or less than three times the size of Earth.
“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,” explained study lead author Dr Soren Meibom from the Harvard-Smithsonian Center for Astrophysics.
The group has measured the age of NGC 6811 to be one billion years. The new exoplanets therefore join a small group of planets with precisely determined ages, distances, and sizes.
“These planets are cosmic extremophiles,” Dr Meibom said.
“Finding them shows that small planets can form and survive for at least a billion years, even in a chaotic and hostile environment.”
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Bibliographic information: Søren Meibom et al. The same frequency of planets inside and outside open clusters of stars. Nature, published online June 26, 2013; doi: 10.1038/nature12279
