Planets seen forming in hostile environment of crowded star clusters

Star clusters with strong radiation and stellar winds seem inhospitable for alien worlds but U.S. scientists say they found two planets in such an environment. Within rich and dense clusters, stars jostle for room with thousands of neighbors while radiation and stellar winds scour interstellar space, stripping planet-forming materials from nearby stars, yet scientists say they have discovered two planets in such an environment. The discovery two planets smaller than Neptune, orbiting sun-like stars 3,000 light-years from Earth, shows planets can develop even in crowded stellar clusters jam-packed with stars, they said. Most stars, including the sun, are born in small, benign groups, while some form in huge, dense swarms that survive for billions of years as stellar clusters. "Old clusters represent a stellar environment much different than the birthplace of the sun and other planet-hosting field stars," lead study author Soren Meibom of the Harvard-Smithsonian Center for Astrophysics said. "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, dubbed Kepler-66b and Kepler 67b, were detected in data gathered by NASA's Kepler planet-hunting spacecraft. "These planets are cosmic extremophiles," Meibom said in a Harvard-Smithsonian release. "Finding them shows that small planets can form and survive for at least a billion years, even in a chaotic and hostile environment."