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Kepler-9 multiple system
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Title: Modeling Kepler transit light curves as false positives: Rejection of blend scenarios for Kepler-9, and validation of Kepler-9d, a super-Earth-size planet in a multiple system
Authors: Guillermo Torres (1), François Fressin (1), Natalie M. Batalha (2), William J. Borucki (3), Timothy M. Brown (4), Stephen T. Bryson (3), Lars A. Buchhave (5), David Charbonneau (1), David R. Ciardi (6), Edward W. Dunham (7), Daniel C. Fabrycky (1), Eric B. Ford (8), Thomas N. Gautier III (9), Ronald L. Gilliland (10), Matthew J. Holman (1), Steve B. Howell (11), Howard Isaacson (12), Jon M. Jenkins (13), David G. Koch (3), David W. Latham (1), Jack J. Lissauer (3), Geoffrey W. Marcy (14), David G. Monet (15), Andrej Prsa (16), Darin Ragozzine (1), Jason F. Rowe (3,17), Dimitar D. Sasselov (1), Jason H. Steffen (18), William F. Welsh (19)
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Light curves from the Kepler Mission contain valuable information on the nature of the phenomena producing the transit-like signals. To assist in exploring the possibility that they are due to an astrophysical false positive, we describe a procedure (BLENDER) to model the photometry in terms of a "blend" rather than a planet orbiting a star. A blend may consist of a background or foreground eclipsing binary (or star-planet pair) whose eclipses are attenuated by the light of the candidate and possibly other stars within the photometric aperture. We apply BLENDER to the case of Kepler-9, a target harboring two previously confirmed Saturn-size planets (Kepler-9b and Kepler-9c) showing transit timing variations, and an additional shallower signal with a 1.59-day period suggesting the presence of a super-Earth-size planet. Using BLENDER together with constraints from other follow-up observations we are able to rule out all blends for the two deeper signals, and provide independent validation of their planetary nature. For the shallower signal we rule out a large fraction of the false positives that might mimic the transits. The false alarm rate for remaining blends depends in part (and inversely) on the unknown frequency of small-size planets. Based on several realistic estimates of this frequency we conclude with very high confidence that this small signal is due to a super-Earth-size planet (Kepler-9d) in a multiple system, rather than a false positive. The radius is determined to be 1.64 (+0.19/-0.14) R(Earth), and current spectroscopic observations are as yet insufficient to establish its mass.

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RE: Kepler 9
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Title: The multiple planets transiting Kepler-9 I. Inferring stellar properties and planetary compositions
Authors: Mathieu Havel (CASSIOPEE), Tristan Guillot (CASSIOPEE), D. Valencia (CASSIOPEE), Aurélien Crida (CASSIOPEE)

The discovery of multiple transiting planetary systems offers new possibilities for the characterisation of exoplanets and the under- standing of their formation. The Kepler-9 system contains two Saturn-mass planets, Kepler-9b and 9c. Using evolution models of gas giants that reproduce the sizes of known transiting planets and accounting for all sources of uncertainties we show that Kepler-9b (respectively 9c) contains 45+17-12 M\oplus (resp. 31+13-10 M\oplus) of hydrogen and helium and 35+10-15 M\oplus (resp. 24+10-12 M\oplus) of heavy elements. More accurate constraints are obtained when comparing planets 9b and 9c: the ratio of the total mass fractions of heavy elements are Zb /Zc = 1.02 ± 0.14, indicating that although the masses of the planets differ, their global composition is very similar, an unexpected result for formation models. Using evolution models for super-Earths, we find that Kepler-9d must contain less than 0.1% of its mass in hydrogen and helium and predict a mostly rocky structure with a total mass between 4 and 16 M\oplus.

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Two huge planets discovered orbiting distant star

The researchers said the two giant planets -- dubbed Kepler 9b and Kepler 9c -- were transiting the star at respective speeds of 19.2 and 38.9 days.
But the speed of their transits increase or decrease by an average of four and 39 minutes respectively, because of the gravitational pull that the planets exert on each other, they reported in the online edition of the Journal Science.

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Posts: 131433
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Kepler-9b and Kepler-9c
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Kepler spies Saturn-sized worlds

The US space agency's Kepler planet-hunter has spied a star that has two Saturn-sized objects circling it.
Astronomers say they cannot be sure just yet but there may be a third, more Earth-sized planet present as well.

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RE: Kepler 9
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NASA's Kepler Mission Discovers Two Planets Transiting the Same Star

NASA's Kepler spacecraft has discovered the first confirmed planetary system with more than one planet crossing in front of, or transiting, the same star.
The transit signatures of two distinct planets were seen in the data for the sun-like star designated Kepler-9. The planets were named Kepler-9b and 9c. The discovery incorporates seven months of observations of more than 156,000 stars as part of an ongoing search for Earth-sized planets outside our solar system. The findings will be published in Thursday's issue of the journal Science.

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Multiple Planets Transiting Same Star Discovered by NASA's Kepler Mission

NASA has announced the discovery of two Saturn-size planets, as well as one likely Earth-size planet, all transiting a star called Kepler 9. This is the first confirmed planetary system with more than one planet transiting the same star.
The observations are published in this week's Science, in an article co-authored by Tim Brown, a UC Santa Barbara-affiliated scientist. The measurements were made using NASA's Kepler spacecraft and were confirmed by the W. M. Keck Observatory in Hawaii.

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NASA's Kepler Mission has discovered the first confirmed planetary system with more than one planet transiting the same star. The announcement of the discovery of the two planets, Kepler 9b and 9c, is based on seven months of observations. Kepler is monitoring more than 156,000 stars for subtle brightness changes as part of an ongoing search for Earth-size planets outside our solar system. Scientists designated the sun-like star Kepler-9.

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