|
〕 | period_year = 0.183 | period_hour = 1600 | semimajor = 0.21847 ± 0.00028〔 | semimajor_gm = | semimajor_mas = | eccentricity = 0〔 | speed = | semi-amp = 1.91 ± 0.22〔 | mean_anomaly = 56 ± 27〔 | epoch = JD 2451409.762〔 }} Gliese 581 d (often shortened to Gl 581 d or GJ 581 d) is a possibly confirmed extrasolar planet orbiting the star Gliese 581 approximately 20.2 light-years〔 away in the constellation of Libra. It is the third planet claimed in the system and (assuming a six-planet model) the fifth in order from the star. Though not confirmed to be a terrestrial planet and significantly more massive than Earth (at 6.98 Earth masses),〔 the Super-Earth is the first exoplanet of terrestrial mass proposed to orbit within the habitable zone of its parent star. Assuming its existence, computer climate simulations have confirmed the possibility of the existence of surface water and these factors combine to a relatively high measure of planetary habitability. It would have an Earth Similarity Index of 0.53.〔 A study in 2014 concluded that Gliese 581 d is "an artifact of stellar activity which, when incompletely corrected, causes the false detection of planet g." But later on, the reanalysis of data suggests planet Gliese 581 d could really exist, despite stellar variability. An additional 2014 study study by Paul Robertson, Suvrath Mahadevan, Michael End, and Arpita Roy concluded that the planet could possibly exist after all, but Gliese 581 g's existence depends on Gliese 581 d's eccentricity.〔http://www.sciencemag.org/content/345/6195/440〕 A study in 2015 by Dr Guillem Anglada-Escudé concluded that the planet does exist. ==Discovery== A team of astronomers led by Stéphane Udry of the Geneva Observatory used the HARPS instrument on the European Southern Observatory 3.6 meter telescope in La Silla, Chile to discover the planet in 2007. Udry's team employed the radial velocity technique, in which the mass of a planet is determined based on the small perturbations it induces in its parent star’s orbit via gravity.〔("The HARPS search for southern extra-solar planets" ), S. Udry. X. Bonfils. X. Delfosse. T. Forveille. M. Mayor. C. Perrier. F. Bouchy. C. Lovis. F. Pepe. D. Queloz. J.-L. Bertaux. The Extrasolar Planets Encyclopaedia. April 4, 2007. Accessed June 10, 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「Gliese 581 d」の詳細全文を読む スポンサード リンク
|