January 27, 2012

Kepler Telescope Finds New Solar Systems

The Kepler Space Telescope (KST), NASA´s planet-hunting observatory, has discovered 26 confirmed planets within 11 new solar systems, including one with five planets all orbiting closer to their sun than Mercury circles ours, scientists told Reuters on Thursday.

The confirmed planets range in size from 1.5 times the radius of Earth to larger than Jupiter. Fifteen of the planets are between Earth and Neptune size. However, it is not yet known which, if any, of these distant worlds are rocky like our own planet.

These discoveries nearly double the number of verified Kepler planets and triple the number of stars known to have more than one planet that passes in front of it. These discoveries will help astronomers better understand how planets form.

“Prior to the Kepler mission, we knew of perhaps 500 exoplanets across the whole sky,” said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. “Now, in just two years staring at a patch of sky not much bigger than your fist, Kepler has discovered more than 60 planets and more than 2,300 planet candidates. This tells us that our galaxy is positively loaded with planets of all sizes and orbits.”

The latest discoveries now boost the list of confirmed extra-solar planets to 729.

KST, launched in March 2009, can detect slight but regular declinations of light from distant stars, typically caused when planets cross in front of them, causing a faint shadow that the telescope is able to pick up.

“Confirming that the small decrease in the star´s brightness is due to a planet requires additional observations and time-consuming analysis,” said Eric Ford, associate professor of astronomy at the University of Florida and lead author of the paper confirming Kepler-23 and Kepler-24.

The astronomers said that none of the newly discovered systems are anything like ours, though Kepler-33, a star older and bigger than our Sun, is among the closest in terms of sheer numbers. It has five planets, compared to our eight.

Each of the 11 new systems discovered contains between two and five closely orbiting planets. In planetary systems where more than one planet is closely transiting a host star, gravitational forces of the planets on each other can cause some to accelerate and others to decelerate along their orbits. The acceleration causes the orbital period of each planet to change. Kepler detects this effect by measuring the so-called Transit Timing Variations.

Planetary systems with Transit Timing Variations can be verified without requiring extensive ground-based observations, accelerating confirmation of planet candidates. Using this detection method, Kepler is able to confirm planetary systems around even fainter and more distant stars.

Five of the discovered systems contain a pair of planets where the inner planet orbit´s the star twice during each orbit of the outer planet. Four of the systems contain two planets where the outer one circles the host star twice for every three times the inner one orbits.

“These configurations help to amplify the gravitational interactions between the planets, similar to how my sons kick their legs on a swing at the right time to go higher,” said Jason Steffen, the Brinson postdoctoral fellow at Fermilab Center for Particle Astrophysics in Batavia, Illinois, and lead author of a paper confirming Kepler-25, 26, 27 and 28.

Jack Lissauer, a planetary scientist with NASA´s Ames Research Center in Moffett Field, California, said the Kepler team have previously found one star with six confirmed planets and another with five planets. Nine of the new systems discovered contain two planets and one has three. Together, with the five planet system, it brings the total number of newly discovered planets to 26, he said.

“This has tripled the number of stars which we know have more than one transiting planet, so that's the big deal here,” Lissauer told Reuters. “We´re starting to think in terms of planetary systems as opposed to just planets: Do they all tend to have similar sizes? What´s the spacing? Is the solar system unusual in those regards?”

The discoveries have been published in four different papers in the Astrophysical Journal and the Monthly Notices of the Royal Astronomical Society.

KST is currently monitoring more than 150,000 stars in the constellations Cygnus and Lyra, trying to find more planetary systems.


Image Caption: This artist's concept shows an overhead view of the orbital position of the planets in systems with multiple transiting planets discovered by NASA's Kepler mission. All the colored planets have been verified. More vivid colors indicate planets that have been confirmed by their gravitational interactions with each other or the star. Several of these systems contain additional planet candidates (shown in grey) that have not yet been verified. (Credit: NASA Ames/UC Santa Cruz)


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