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HD 80606 b (also Struve 1341 B b or HIP 45982 b) is an eccentric Jupiter 190 light-years from the Sun in the constellation of Ursa Major. HD 80606 b was discovered orbiting the star Struve 1341 B in April 2001 by a team led by Michel Mayor and Didier Queloz.〔 With a mass 4 times that of Jupiter, it is a gas giant. Because the planet transits the host star its radius can be determined using the transit method and was found to be slightly smaller than Jupiter's. Its density is slightly less than Earth's.〔 ==Physical properties== HD 80606 b has the most eccentric orbit of any known planet after HD 20782 b. Its eccentricity is 0.9336, comparable to Halley's Comet. The eccentricity may be a result of the Kozai mechanism, which would occur if the planet's orbit is significantly inclined to that of the binary stars. This interpretation is supported by measurements of the Rossiter–McLaughlin effect, which indicate that the planet's orbit may be significantly inclined (by approximately 50 degrees) to the rotational axis of the star, a configuration which would be expected if the Kozai mechanism were responsible for the orbit.〔 As a result of this high eccentricity, the planet's distance from its star varies from 0.03 to 0.88 AU. At apastron it would receive an insolation similar to that of Earth, while at periastron the insolation would be around 800 times greater, far more than that experienced by Mercury in the Solar System. In 2009, the eclipse of HD 80606 b by its parent star was detected, allowing measurements of the planet's temperature to be made as the planet passed through periastron. These measurements indicated that the temperature rose from around 800 K (500 °C / 1000 °F) to 1500 K (1200 °C / 2200 °F) in just 6 hours.〔 An observer above the cloud tops of the gas giant would see the parent star swell to 30 times the apparent size of the Sun in our own sky. The transit was detected using a Celestron 35-cm Schmidt–Cassegrain telescope.〔 Prior to the large data release of the Kepler Mission in February 2011, HD 80606 b has the longest orbital period of any known transiting planet. It takes 12.1 hours to transit its star. The transit of 14 January 2010 was partially observed by MOST; but there were equipment failures over part of this time, and the 8 January secondary transit was entirely lost. The midpoint of the next transit is 1 February 2013 11:37 UT.〔(HD 80606 Transit Times - Variable Star and Exoplanets )〕 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「HD 80606 b」の詳細全文を読む スポンサード リンク
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