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  • 1
    Publication Date: 2011-12-22
    Description: Since the discovery of the first extrasolar giant planets around Sun-like stars, evolving observational capabilities have brought us closer to the detection of true Earth analogues. The size of an exoplanet can be determined when it periodically passes in front of (transits) its parent star, causing a decrease in starlight proportional to its radius. The smallest exoplanet hitherto discovered has a radius 1.42 times that of the Earth's radius (R( plus sign in circle)), and hence has 2.9 times its volume. Here we report the discovery of two planets, one Earth-sized (1.03R( plus sign in circle)) and the other smaller than the Earth (0.87R( plus sign in circle)), orbiting the star Kepler-20, which is already known to host three other, larger, transiting planets. The gravitational pull of the new planets on the parent star is too small to measure with current instrumentation. We apply a statistical method to show that the likelihood of the planetary interpretation of the transit signals is more than three orders of magnitude larger than that of the alternative hypothesis that the signals result from an eclipsing binary star. Theoretical considerations imply that these planets are rocky, with a composition of iron and silicate. The outer planet could have developed a thick water vapour atmosphere.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fressin, Francois -- Torres, Guillermo -- Rowe, Jason F -- Charbonneau, David -- Rogers, Leslie A -- Ballard, Sarah -- Batalha, Natalie M -- Borucki, William J -- Bryson, Stephen T -- Buchhave, Lars A -- Ciardi, David R -- Desert, Jean-Michel -- Dressing, Courtney D -- Fabrycky, Daniel C -- Ford, Eric B -- Gautier, Thomas N 3rd -- Henze, Christopher E -- Holman, Matthew J -- Howard, Andrew -- Howell, Steve B -- Jenkins, Jon M -- Koch, David G -- Latham, David W -- Lissauer, Jack J -- Marcy, Geoffrey W -- Quinn, Samuel N -- Ragozzine, Darin -- Sasselov, Dimitar D -- Seager, Sara -- Barclay, Thomas -- Mullally, Fergal -- Seader, Shawn E -- Still, Martin -- Twicken, Joseph D -- Thompson, Susan E -- Uddin, Kamal -- England -- Nature. 2011 Dec 20;482(7384):195-8. doi: 10.1038/nature10780.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA. ffressin@cfa.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22186831" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2012-01-13
    Description: Most Sun-like stars in the Galaxy reside in gravitationally bound pairs of stars (binaries). Although long anticipated, the existence of a 'circumbinary planet' orbiting such a pair of normal stars was not definitively established until the discovery of the planet transiting (that is, passing in front of) Kepler-16. Questions remained, however, about the prevalence of circumbinary planets and their range of orbital and physical properties. Here we report two additional transiting circumbinary planets: Kepler-34 (AB)b and Kepler-35 (AB)b, referred to here as Kepler-34 b and Kepler-35 b, respectively. Each is a low-density gas-giant planet on an orbit closely aligned with that of its parent stars. Kepler-34 b orbits two Sun-like stars every 289 days, whereas Kepler-35 b orbits a pair of smaller stars (89% and 81% of the Sun's mass) every 131 days. The planets experience large multi-periodic variations in incident stellar radiation arising from the orbital motion of the stars. The observed rate of circumbinary planets in our sample implies that more than approximately 1% of close binary stars have giant planets in nearly coplanar orbits, yielding a Galactic population of at least several million.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Welsh, William F -- Orosz, Jerome A -- Carter, Joshua A -- Fabrycky, Daniel C -- Ford, Eric B -- Lissauer, Jack J -- Prsa, Andrej -- Quinn, Samuel N -- Ragozzine, Darin -- Short, Donald R -- Torres, Guillermo -- Winn, Joshua N -- Doyle, Laurance R -- Barclay, Thomas -- Batalha, Natalie -- Bloemen, Steven -- Brugamyer, Erik -- Buchhave, Lars A -- Caldwell, Caroline -- Caldwell, Douglas A -- Christiansen, Jessie L -- Ciardi, David R -- Cochran, William D -- Endl, Michael -- Fortney, Jonathan J -- Gautier, Thomas N 3rd -- Gilliland, Ronald L -- Haas, Michael R -- Hall, Jennifer R -- Holman, Matthew J -- Howard, Andrew W -- Howell, Steve B -- Isaacson, Howard -- Jenkins, Jon M -- Klaus, Todd C -- Latham, David W -- Li, Jie -- Marcy, Geoffrey W -- Mazeh, Tsevi -- Quintana, Elisa V -- Robertson, Paul -- Shporer, Avi -- Steffen, Jason H -- Windmiller, Gur -- Koch, David G -- Borucki, William J -- England -- Nature. 2012 Jan 11;481(7382):475-9. doi: 10.1038/nature10768.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Astronomy Department, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, USA. wfw@sciences.sdsu.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22237021" target="_blank"〉PubMed〈/a〉
    Keywords: Extraterrestrial Environment/chemistry ; *Planets ; Space Flight ; Spacecraft ; Stars, Celestial
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2011-02-05
    Description: When an extrasolar planet passes in front of (transits) its star, its radius can be measured from the decrease in starlight and its orbital period from the time between transits. Multiple planets transiting the same star reveal much more: period ratios determine stability and dynamics, mutual gravitational interactions reflect planet masses and orbital shapes, and the fraction of transiting planets observed as multiples has implications for the planarity of planetary systems. But few stars have more than one known transiting planet, and none has more than three. Here we report Kepler spacecraft observations of a single Sun-like star, which we call Kepler-11, that reveal six transiting planets, five with orbital periods between 10 and 47 days and a sixth planet with a longer period. The five inner planets are among the smallest for which mass and size have both been measured, and these measurements imply substantial envelopes of light gases. The degree of coplanarity and proximity of the planetary orbits imply energy dissipation near the end of planet formation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lissauer, Jack J -- Fabrycky, Daniel C -- Ford, Eric B -- Borucki, William J -- Fressin, Francois -- Marcy, Geoffrey W -- Orosz, Jerome A -- Rowe, Jason F -- Torres, Guillermo -- Welsh, William F -- Batalha, Natalie M -- Bryson, Stephen T -- Buchhave, Lars A -- Caldwell, Douglas A -- Carter, Joshua A -- Charbonneau, David -- Christiansen, Jessie L -- Cochran, William D -- Desert, Jean-Michel -- Dunham, Edward W -- Fanelli, Michael N -- Fortney, Jonathan J -- Gautier, Thomas N 3rd -- Geary, John C -- Gilliland, Ronald L -- Haas, Michael R -- Hall, Jennifer R -- Holman, Matthew J -- Koch, David G -- Latham, David W -- Lopez, Eric -- McCauliff, Sean -- Miller, Neil -- Morehead, Robert C -- Quintana, Elisa V -- Ragozzine, Darin -- Sasselov, Dimitar -- Short, Donald R -- Steffen, Jason H -- England -- Nature. 2011 Feb 3;470(7332):53-8. doi: 10.1038/nature09760.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉NASA Ames Research Center, Moffett Field, California 94035, USA. jack.lissauer@nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21293371" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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