|Discovery date||2011 |
|Orbital characteristics |
|Epoch JD 2457000.5 (2014-Dec-09)|
|83.59 yr (30,530 ± 4 d)|
|Dimensions||~ 60 km |
|9.6 (r-band) 
2011 QF99 is the first and, as of 2015, the only known Uranus trojan. It was discovered in 2011 during a deep survey of trans-Neptunian objects conducted with the Canada–France–Hawaii Telescope. It is believed to be roughly 60 km in diameter, assuming an albedo of 0.05.
2011 QF99 temporarily orbits near Uranus's L4 Langrangian point (leading Uranus). It will continue to librate around L4 for at least 70,000 years and will remain a Uranus co-orbital for up to three million years before becoming a centaur. 2011 QF99 is thus a temporary Uranus trojan—a centaur captured some time ago.
Uranus trojans are generally expected to be unstable and none of them are thought to be of primordial origin. A simulation led to the conclusion that at any given time, 0.4% of the centaurs in the scattered population within 34 AU would be Uranus co-orbitals, of which 64% (0.256% of all centaurs) would be in horseshoe orbits, 10% (0.04%) would be quasi-satellites, and 26% (0.104%) would be trojans (evenly split between the L4 and L5 groups).
- "JPL Small-Body Database Browser: 2011 QF99". Retrieved 2013-03-29.
- Alexandersen, M.; Gladman, B.; Greenstreet, S.; Kavelaars, J. J.; Petit, J. -M.; Gwyn, S. (2013). "A Uranian Trojan and the Frequency of Temporary Giant-Planet Co-Orbitals". Science 341 (6149): 994–997. arXiv:1303.5774. doi:10.1126/science.1238072. PMID 23990557.
- Choi, C. Q. (2013-08-29). "First 'Trojan' Asteroid Companion of Uranus Found". Space.com web site. TechMediaNetwork. Retrieved 2013-09-03.
- Alexandersen, M.; Kavelaars, J.; Petit, J.; Gladman, B. (18 March 2013). "MPEC 2013-F19: 2011 QF99". IAU. Retrieved 3 September 2013.
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