Two planets, a star, and a solar system

February 14, 2008 12:30:54 PM PST
In a solar system thousands of light years away, a star about half the size of our sun is being orbited by two planets that seem like smaller versions of Jupiter and Saturn, astronomers report. The simultaneous discovery of two planets is rare and this was the first time researchers had the opportunity to do so using a technique called gravitational microlensing.

"You could call it luck, but I think it might just mean that these systems are common throughout our galaxy," said Scott Gaudi of Ohio State University, lead author of the report in Friday's issue of the journal Science.

The star and its planets were observed when they passed in front of a more distant star in 2006. A lensing effect magnified the light of the distant star 500 times, the researchers explained.

Gaudi analyzed the data and discovered a distortion that he thought was caused by a Saturn-mass planet. Then, less than a day later, came an additional distortion he wasn't expecting: a "blip" in the signal that appeared to be caused by a second, larger planet orbiting the same star.

It took two months to confirm the two-planet find. David Bennett, a research associate professor of astrophysics and cosmology at the University of Notre Dame, refined the preliminary model revealing additional details about the system.

The researchers said the newly discovered planets appear to be gaseous, like Jupiter and Saturn, but only about 80 percent as big. "This is the first time we had a high enough magnification event where we had significant sensitivity to a second planet - and we found one," Gaudi said in a statement.

Four single planets have been found previously using microlensing, two of them by the Ohio State University-based Microlensing Follow Up Network - MicroFUN.

This work was funded by the National Science Foundation; NASA; the Polish Ministry of Scientific Research and Information Technology; the SRC Korea Science & Engineering Foundation; the Korea Astronomy & Space Science Institute; German Research Council; Particle Physics and Astronomy Research Council; the European Union Program for Research and Technological Development; the Israel Science Foundation; the Marsden Fund of New Zealand; the Japan Ministry of Education, Culture, Sports, Science and Technology and the Japan Society for the Promotion of Science.

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