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Kepler-12b is a Hot Jupiter that orbits G-type star Kepler-12 some 600 parsecs away. The planet has an anomalously large radius that could not be explained by standard models at the time of its discovery, as it is almost 1.7 times Jupiter's size while being 0.4 times Jupiter's mass. The planet was detected by the Kepler spacecraft, a NASA project searching for planets that transit (cross in front of) their host stars. The discovery paper was published on September 5, 2011. ==Discovery== NASA's Kepler spacecraft continuously observes a region of the night sky, searching for signs of transiting planets. While orbiting their host stars, such transiting planets cross in front of host stars as seen from Earth. The slight and periodic dimming in the star's brightness is used to determine whether or not the dimming was caused by a planet and not by a false positive. Analysis of Kepler's early data yielded evidence of a transit signal around a star designated as KIC 11804465, later known as Kepler-12. The transit signal was designated KOI-20.〔 The Kepler Follow-up Program (KFOP) worked to verify the existence of the planet. KFOP used the W.M. Keck Observatory's Keck I telescope to prove that Kepler-12 was not an eclipsing binary star (a possible false positive that mimics the transit signal). The WIYN Observatory, which was used for speckle imaging, supported Keck's findings and verified that the signal caused by KOI-20 was not caused by a nearby background star's interference. Adaptive optics imaging in the near-infrared was obtained on September 9, 2009 with the Palomar Observatory's PHARO camera on the Hale telescope confirmed both the WIYN and Keck findings.〔 Keck's HIRES instrument measured Kepler-12's radial velocity, which was used to find more of Kepler-12's characteristics (and, by extension, deduce the characteristics of KOI-20 itself). The radial velocity measurements eventually led to the confirmation of Kepler-12b as a planet.〔 Kepler's data in its first 1.5 years of operation was processed and analyzed, yielding Kepler-12b's radius, mass and density.〔 The Spitzer Space Telescope's IRAC infrared adaptive optics camera was used to carried out program #60028, which observed the occultations by several giant planets detected by Kepler behind their host stars. The Kepler team, using the observations, tentatively concluded that Kepler-12b most likely did not experience a temperature inversion, in which the day-side temperature of the planet is lower than the night-side. Kepler-12b's discovery paper was published in the ''Astrophysical Journal'' on September 5, 2011.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Kepler-12b」の詳細全文を読む スポンサード リンク
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