2011 QF99

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2011 QF99
Discovery date 2011[1]
Orbital characteristics[1][2]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 3
Observation arc 1449 days (3.97 yr)
Aphelion 22.487 AU (3.3640 Tm)
Perihelion 15.676 AU (2.3451 Tm)
19.081 AU (2.8545 Tm)
Eccentricity 0.17846
83.35 yr (30445 d)
0° 0m 42.57s /day
Inclination 10.8233°
Earth MOID 14.7043 AU (2.19973 Tm)
Jupiter MOID 10.4391 AU (1.56167 Tm)
Physical characteristics
Dimensions ~60 km[2]
0.05 (assumed)
9.6 (r-band)[2]

2011 QF99 is the first and, as of 2015, the only known Uranus trojan.[2][3] It was discovered in 2011 during a deep survey of trans-Neptunian objects conducted with the Canada–France–Hawaii Telescope.[2][4] It is thought to be roughly 60 km in diameter, assuming an albedo of 0.05.[2]

2011 QF99 temporarily orbits near Uranus's L4 Lagrangian 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.[2]

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).[2]


  1. ^ a b c "JPL Small-Body Database Browser: 2011 QF99". Retrieved 31 March 2016. 
  2. ^ a b c d e f g h 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:1303.5774free to read. Bibcode:2013Sci...341..994A. doi:10.1126/science.1238072. PMID 23990557. 
  3. ^ Choi, C. Q. (2013-08-29). "First 'Trojan' Asteroid Companion of Uranus Found". Space.com web site. TechMediaNetwork. Retrieved 2013-09-03. 
  4. ^ 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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