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Dia (), also known as Jupiter LIII, is the second-outermost known prograde irregular satellite of Jupiter. Provisionally known as S/2000 J 11, it received its name on 7 March 2015.〔CBET (Central Bureau Electronic Telegram) 4075: 20150307: SATELLITES OF JUPITER, 7 March 2015〕 It is named after Dia, daughter of Deioneus (or Eioneus), wife of Ixion. According to Homer, she was seduced by Zeus in stallion form; Pirithous was the issue. The satellite is the only known small body in the Himalia group.〔Sheppard, S. S.; Jewitt, D. C.; (''An abundant population of small irregular satellites around Jupiter'' ), Nature, 423 (May 2003), pp. 261-263〕 Dia is believed to be about 4 kilometres in diameter.〔Sheppard, S. S.; Jewitt, D. C.; Porco, C.; (''Jupiter's outer satellites and Trojans'' ), in ''Jupiter: The planet, satellites and magnetosphere,'' edited by Fran Bagenal, Timothy E. Dowling, William B. McKinnon, Cambridge Planetary Science, Vol. 1, Cambridge, UK: Cambridge University Press, ISBN 0-521-81808-7, 2004, pp. 263-280〕 It orbits Jupiter at an average distance of 12 million km in 274 days, at an inclination of 28° (to Jupiter's equator), and with an eccentricity of 0.21.〔 ==Observational history== Dia was discovered by a team of astronomers from the University of Hawaii led by Scott S. Sheppard in 2000 with an observation arc of 26 days.〔(IAUC 7555: ''Satellites of Jupiter'' ) 2001 January 5 (discovery)〕〔(MPEC 2001-A29: ''S/2000 J 7, S/2000 J 8, S/2000 J 9, S/2000 J 10, S/2000 J 11'' ) 2001 January 15 (discovery and ephemeris)〕 Initial observations were not followed up, and Dia was not observed for more than a decade after 2000. This apparent disappearance led some astronomers to consider the moon lost. One theory was that it had crashed into Himalia, creating a faint ring around Jupiter.〔("Lunar marriage may have given Jupiter a ring" ), New Scientist, March 20, 2010, p. 16.〕 However, it was finally recovered in observations made in 2010 and 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「Dia (moon)」の詳細全文を読む スポンサード リンク
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