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(also written 2001 QR322) was the first Neptune trojan discovered, in 2001 by the Deep Ecliptic Survey. It orbits ahead of Neptune at its Lagrangian point.〔 With an absolute magnitude of 7.8〔(【引用サイトリンク】title=JPL Small-Body Database Browser: (2001 QR322) )〕 to 8.2,〔 it has a diameter in the range of 60 to 160 km. Other Neptune trojans have been discovered since. A study by Scott S. Sheppard and Chad Trujillo from the Carnegie Institution suggests that Neptune could possibly have twenty times more trojans than Jupiter. ==Dynamical stability== Early studies of the dynamical stability of , which used a small number of test particles spread over the uncertainties of just a few orbital parameters that were derived from a limited observation arc, suggested that is on a remarkably stable orbit, because most test particles remained on trojan orbits for 5 Gyr. Thereafter, the stability of Neptune trojans was simply assumed.〔 A more recent study, which used a very large number of test particles spread over the 3σ uncertainties in all six orbital parameters derived from a longer observational arc, has indicated that is far less dynamically stable than previously thought.〔 The test particles were lost exponentially with a half life of 553 Myr.〔 Further observations can determine whether 's orbit is actually within the dynamically stable or within the unstable part.〔 The stability is strongly dependent on semi-major axis, with a≥30.30 AU being far less stable, but only very weakly dependent on the other orbital parameters.〔 This is because those with larger semi-major axes have larger libration amplitudes, with amplitudes ~70° and above being destabilized by secondary resonances between the trojan motion and the dynamics of at least Saturn, Uranus, and Neptune.〔 Secular resonances were found not to contribute to the dynamical stability of .〔 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「2001 QR322」の詳細全文を読む スポンサード リンク
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