August 26, 2010
Kepler Spacecraft Finds New Planetary System
NASA reported on Thursday that its Kepler spacecraft discovered a planetary system with two planets crossing in front of the same star.
This is the first planetary system discovered with more than one planet transiting in front of the same star. The two planets were named Kepler-9b and 9c. The findings were published in Thursday's issue of the journal Science.
Kepler's camera measures tiny decreases in the stars' brightness that occurs when a planet transits in from of them. This discovery comes after seven months of observations of over 156,000 stars.
The distance of the planet from the star is measured by the time between successive dips as the planet orbits.
Mission scientists submitted findings for peer review in June that identified over 700 planet candidates in the first 43 days of Kepler data.
The Kepler team recently found a sixth target exhibiting multiple transits, which helped confirm the Kepler 9b and 9c.
"Kepler's high quality data and round-the-clock coverage of transiting objects enable a whole host of unique measurements to be made of the parent stars and their planetary systems," said Doug Hudgins, the Kepler program scientist at NASA Headquarters in Washington.
NASA said that the planet Kepler-9b orbits closer to the star than Kepler-9c. This planet takes 19 days to completely orbit the star, while Kepler-9c orbits in about 38 days.
"This discovery is the first clear detection of significant changes in the intervals from one planetary transit to the next, what we call transit timing variations," said Matthew Holman, a Kepler mission scientist from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "This is evidence of the gravitational interaction between the two planets as seen by the Kepler spacecraft."
Kepler scientists have also discovered a third transit of the Kepler-9 planetary system. However, NASA reported that more observations are needed in order to determine whether this third transit is a planet or not.
Image Caption: This artist's concept illustrates the two Saturn-sized planets discovered by NASA's Kepler mission. The star system is oriented edge-on, as seen by Kepler, such that both planets cross in front, or transit, their star, named Kepler-9. This is the first star system found to have multiple transiting planets. Image credit: NASA/Ames/JPL-Caltech
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