TAU researchers help discover new planet

Cool Jupiter-sized planet orbits a star some 1,500 light years away from the Earth.

By JUDY SIEGEL-ITZKOVICH
corot 9b planet 311 (photo credit: Tel Aviv University)
corot 9b planet 311
(photo credit: Tel Aviv University)
An international scientific team including two Israeli astronomers from Tel Aviv University has discovered a cool, Jupiter-sized planet orbiting a star some 1,500 light years away from the Earth. The discovery was published Wednesday in the journal Nature. The lead TAU researchers were Prof. Zvi Mazeh and his student Avi Shporer.
The planet, called CoRoT 9b, was initially detected by the French CoRoT satellite when it transited in front of its parent star, causing the star’s observed brightness to drop.
The CoRoT satellite is run by the French Space Agency (CNES), which said the newly discovered planet was approximately the size of Jupiter, orbited its sun once every 95 days and was relatively cool.
Hans Deeg of the Institute of Astrophysics in the Canary Islands, which heads the research group, explained on Wednesday that of all the exoplanets (planets outside our solar system) to be discovered to date due to transits, CoRoT 9b was the first to have a moderate temperature (between -20 to +150 degrees Celsius). The exact temperature depends on the planet’s atmosphere and its ability to absorb the radiation of its sun, he explained.
The CoRoT 9b transit was first observed by the CoRoT satellite after continuous observation of its parent star over a 150-day period in 2008. On the basis of this data, researchers made observations of the planet from various locations around the world, including TAU’s facility in the Negev, and others in Chile, Hawaii and the Canary Islands. The terrestrial observations confirmed the find was indeed a new planet.
Despite its great distance from Earth, both the size and mass of the planet could be estimated from the observations. During the past decade, this had been possible only if such planets orbited very close to their suns, said Mazeh.
“Until now, the measurement of planetary mass was very much influencedby the massive radiation they [exoplanets] absorb from their suns.However, the new one [CoRoT 9b] is the first to be discovered whosemass could be assessed even though it rotates around its sun at a greatdistance. Thus it provides a clear test of existing theories about theway giant planets are developed. Measured density is suited to theassessment of these theories.”
The new planet is comprised mainly of hydrogen and helium, according toTristan Guillot of the observation center in Nice on the FrenchRiviera, “But it is liable to contain up to 20 times the mass of Earthin the form of ice and dense rock. Thus it is similar to the largestplanets in our solar system – Jupiter and Saturn.”
Mazeh said that recent advances in the study of exoplanets have been tremendous.
“It’s amazing to think that 25 years ago, not a single planet like thiswas known. In a relatively short time, many different solar systems –some of them with planets very different from those in our solar system– have been discovered. The university presents us many moresurprises,” he concluded.