First transiting planets in a star cluster discovered
by Elizabeth Howell
(Phys.org) —All stars begin their lives in groups. Most stars, including our Sun, are born in small, benign groups that quickly fall apart. Others form in huge, dense swarms that survive for billions of years as stellar clusters. Within such rich and dense clusters, stars jostle for room with thousands of neighbors while strong radiation and harsh stellar winds scour interstellar space, stripping planet-forming materials from nearby stars.
It would thus seem an unlikely place to find alien worlds. Yet 3,000 light-years from Earth, in the star cluster NGC 6811, astronomers have found two planets smaller than Neptune orbiting Sun-like stars. The discovery, published in the journal Nature, shows that planets can develop even in crowded clusters jam-packed with stars.
"Old clusters represent a stellar environment much different than the birthplace of the Sun and other planet-hosting field stars," says lead author Soren Meibom of the Harvard-Smithsonian Center for Astrophysics (CfA). "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."
The two new alien worlds appeared in data from NASA's Kepler spacecraft. Kepler hunts for planets that transit, or cross in front of, their host stars. During a transit, the star dims by an amount that depends on the size of the planet, allowing the size to be determined. Kepler-66b and Kepler-67b are both less than three times the size of Earth, or about three-fourths the size of Neptune (mini-Neptunes).
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http://phys.org/news/2013-06-transiting-planets-star-cluster.html
Nightfall, anyone?
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