* Astronomy

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RE: Kepler-47b

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'Tatooine-like' double-star systems can host planets

A new study shows that planetary systems can form and survive in the chaotic environment around pairs of stars.
A team reports in Science the discovery of two planets orbiting a pair of stars - a so-called binary.
The planetary system, known as Kepler-47, is located roughly 5,000 light-years away, in the constellation Cygnus.
It contains a pair of stars whizzing around each other every 7.5 days. One star is Sun-like, while the other is about one-third the size of its neighbour and 175 times fainter.
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Title: Kepler-47: A Transiting Circumbinary Multi-Planet System
Authors: Jerome A. Orosz, William F. Welsh, Joshua A. Carter, Daniel C. Fabrycky, William D. Cochran, Michael Endl, Eric B. Ford, Nader Haghighipour, Phillip J. MacQueen, Tsevi Mazeh, Roberto Sanchis-Ojeda, Donald R. Short, Guillermo Torres, Eric Agol, Lars A. Buchhave, Laurance R. Doyle, Howard Isaacson, Jack J. Lissauer, Geoffrey W. Marcy, Avi Shporer, Gur Windmiller, Thomas Barclay, Alan P. Boss, Bruce D. Clarke, Jonathan Fortney, John C. Geary, Matthew J. Holman, Daniel Huber, Jon M. Jenkins, Karen Kinemuchi, Ethan Kruse, Darin Ragozzine, Dimitar Sasselov, Martin Still, Peter Tenenbaum, Kamal Uddin, Joshua N. Winn, David G. Koch, William J. Borucki

We report the detection of Kepler-47, a system consisting of two planets orbiting around an eclipsing pair of stars. The inner and outer planets have radii 3.0 and 4.6 times that of the Earth, respectively. The binary star consists of a Sun-like star and a companion roughly one-third its size, orbiting each other every 7.45 days. With an orbital period of 49.5 days, eighteen transits of the inner planet have been observed, allowing a detailed characterisation of its orbit and those of the stars. The outer planet's orbital period is 303.2 days, and although the planet is not Earth-like, it resides within the classical "habitable zone", where liquid water could exist on an Earth-like planet. With its two known planets, Kepler-47 establishes that close binary stars can host complete planetary systems.

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NASA's Kepler Discovers Multiple Planets Orbiting a Pair of Stars

Coming less than a year after the announcement of the first circumbinary planet, Kepler-16b, NASA's Kepler mission has discovered multiple transiting planets orbiting two suns for the first time. This system, known as a circumbinary planetary system, is 4,900 light-years from Earth in the constellation Cygnus.
This discovery proves that more than one planet can form and persist in the stressful realm of a binary star and demonstrates the diversity of planetary systems in our galaxy.
Astronomers detected two planets in the Kepler-47 system, a pair of orbiting stars that eclipse each other every 7.5 days from our vantage point on Earth. One star is similar to the sun in size, but only 84 percent as bright. The second star is diminutive, measuring only one-third the size of the sun and less than 1 percent as bright.
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