Kepler Planet-Hunting Mission Finds 5ew Lightweight Worlds

WASHINGTON — The list of known exoplanets inthe galaxy just got bigger, thanks to the first observations ofASA'sKepler space telescope, which found five new lightweight worlds orbitingdistant stars."Iwould like to announce today the discovery of five exoplanets by Kepler,"said Kepler science director William Borucki ofASA's Ames Research Center in Moffett Field, Calif., here today at the 215th meeting of the American AstronomicalSociety.Theplanet-hunting Kepler, which hopes to discover alien Earths, also found an oddobject orbiting a star and is measuring the quakes that ripple across stellarsurface.The five newfoundplanets are all much larger than the Earth-sizedbodies Kepler was designed to find, with one coming in at around the sizeofeptune, and the other four measuring larger than Jupiter.All fiveplanets orbit very close to their stars, with orbital periods of around threeto four days, and so are very hot. Their temperatures are above those of moltenlava; even iron would melt on their surfaces."Sothese are very hot, very bright planets," Borucki said.While theNeptune-sized planets, dubbed Kepler 4b, is about the density of the ice giantsin our solar system (and so likely has an abundance of elements heavier thanhydrogen and helium), one of the other newfound planets, Kepler 7b, has one ofthe lowest densities of any planet ever discovered, Borucki said.While theseplanets aren't the type that scientists hope Kepler will ultimately find, theobservations that the telescope has made so far show that "we do have thesensitivity to find Earth-size planets," Borucki said.Kepler,which launched on March 6, 2009, looksfor dips in the light curves of stars that indicate a planet transiting infront of the star (from the perspective of Earth).Kepler alsoobserves occultations of planets, or the light curve dips that occur when theplanet moves behind its parent star. The telescope has made one strangeobservation of a system where the light curve from the orbiting body dips moreduring the occultation than during its transit, which suggests that it is muchhotter than its parent star – certainly an odd situation for a planet-star system.The body could be a small, relatively cool white dwarf, but its size is too bigfor a white dwarf."Sowe're not quite sure what we're seeing here," Borucki said.Kepler hasalso shown its ability to measure the oscillations that occur at a star's surfacethat cause it to "ring like a bell" and its brightness to vary.Studying this stellar seismology can help scientists better understand the ageand structure of stars. Kepler data for one star has pinned down that star'sdiameter from within a 10 percent margin of error to within 1 percent."Thisin turn gives astronomers much better knowledge of the planet's density, in thecase studied this has improved from about 50 percent uncertainty to fivepercent, which is very important for understanding exoplanets, said RonGilliland of the Space Science Institute in Baltimore, Md., and the principalinvestigator for Kepler's astroseismology program.The resultsannounced at the meeting come from just the first 43 days of Keplerobservations; scientists now have more than eight months of data to combthrough, Borucki said.Video– Hunting Alien Earths: Kepler Stares at StarsTop 10Most Intriguing Extrasolar PlanetsHowKepler Searches for ExoplanetsOriginal Story: Kepler Planet-Hunting Mission Finds 5ew Lightweight WorldsSPACE.com offers rich and compelling content about space science, travel and exploration as well as astronomy, technology, business news and more. The site boasts a variety of popular features including our space image of the day and other space pictures,space videos, Top 10s, Trivia, podcasts and Amazing Images submitted by our users. Join our community, sign up for our free newsletters and register for our RSS Feeds today!