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Siarnaq ( ), or Saturn XXIX, is a prograde irregular satellite of Saturn. It was discovered by Brett J. Gladman, et al. in 2000,〔(IAUC 7513: ''S/2000 S 3 and S/2000 S 4'' ) October 25, 2000 (discovery)〕〔(MPEC 2000-Y14: ''S/2000 S 3, S/2000 S 4, S/2000 S 5, S/2000 S 6, S/2000 S 10'' ) December 19, 2000 (discovery and ephemeris)〕 and given the temporary designation S/2000 S 3. Named after the giant Siarnaq of Inuit mythology,〔(IAUC 8177: ''Satellites of Jupiter, Saturn, Uranus'' ) August 8, 2003 (naming the moon)〕 it is the largest member of the Inuit group of irregular satellites. Siarnaq is thought to be about 40 kilometers in diameter. It orbits Saturn at an average distance of 17.5 Gm in 895 days. The rotation period was measured by the Cassini spacecraft to approximately 10 hours and 9 minutes;〔 this is the shortest rotation period of all prograde irregular moons of Saturn. It is light red in color, and the Siarnaupian (Siarnaqan) spectrum in the infrared is very similar to the Inuit-group satellites Paaliaq and Kiviuq, supporting the thesis of a possible common origin in the break-up of a larger body.〔〔Gladman, B. J.; Nicholson, P. D.; Burns, J. A.; Kavelaars, J. J.; Marsden, B. G.; Holman, M. J.; Grav, T.; Hergenrother, C. W.; Petit, J.-M.; Jacobson, R. A.; and Gray, W. J.; (''Discovery of 12 satellites of Saturn exhibiting orbital clustering'' ), Nature, 412 (July 12, 2001), pp. 163–166〕〔Grav, T.; Holman, M. J.; Gladman, B. J.; Aksnes, K.; (''Photometric survey of the irregular satellites'' ), Icarus, 166 (2003), pp. 33-45〕 Siarnaq has been found to be in a secular resonance with Saturn, involving the precession of its periapsis and that of the planet.〔 Ćuk, M.; Burns, J. A.; (''On the Secular Behavior of Irregular Satellites'' ), The Astronomical Journal, 128 (2004), pp. 2518-2541〕1 The studies of these resonances are key to understand the capture mechanism for the irregular satellites and, assuming a common origin of a given dynamical group in the break-up of a single body, to explain today’s dispersion of the orbital elements. 1The ecliptic longitudes of the periapsis of the satellite and the planet are locked. == References == *Ephemeris (IAU-MPC NSES ) 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「Siarnaq」の詳細全文を読む スポンサード リンク
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