2011 QF99

Asteroid 2011 QF99 is a minor planet from the outer Solar System and the first known Uranus trojan to be discovered. It measures approximately 60 kilometers in diameter, assuming an albedo of 0.05.[2][4] It was first observed 29 August 2011 during a deep survey of trans-Neptunian objects conducted with the Canada–France–Hawaii Telescope, but its identification as Uranian trojan was not announced until 2013.[2][5]

2011 QF99
Discovery
Discovery siteMauna Kea Obs.
Discovery date29 August 2011[1]
(first observation only)
Designations
2011 QF99
Uranus trojan [2]
centaur [1] · distant [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 3
Observation arc3.97 yr (1,449 days)
Aphelion22.422 AU
Perihelion15.659 AU
19.040 AU
Eccentricity0.1776
83.08 yr (30,346 days)
283.84°
0° 0m 42.84s / day
Inclination10.833°
222.52°
288.25°
Physical characteristics
Dimensions60 km (calculated)[2]
0.05 (assumed)[2]
9.6 (R-band)[2]
9.7[1]

    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][6]

    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] A second Uranian Trojan, 2014 YX49, was announced in 2017.[7]

    References
    1. "JPL Small-Body Database Browser: (2011 QF99)" (2012-10-21 last obs.). Jet Propulsion Laboratory. Retrieved 12 October 2017.
    2. 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. Bibcode:2013Sci...341..994A. doi:10.1126/science.1238072. PMID 23990557.
    3. "2011 QF99". Minor Planet Center. Retrieved 12 October 2017.
    4. Choi, C. Q. (29 August 2013). "First 'Trojan' Asteroid Companion of Uranus Found". Space.com web site. TechMediaNetwork. Retrieved 3 September 2013.
    5. Alexandersen, M.; Kavelaars, J.; Petit, J.; Gladman, B. (18 March 2013). "MPEC 2013-F19: 2011 QF99". IAU. Retrieved 3 September 2013. Cite journal requires |journal= (help)
    6. de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (22 May 2014). "Comparative orbital evolution of transient Uranian co-orbitals: exploring the role of ephemeral multibody mean motion resonances". Monthly Notices of the Royal Astronomical Society. 441 (3): 2280–2295. arXiv:1404.2898. Bibcode:2014MNRAS.441.2280D. doi:10.1093/mnras/stu733.
    7. de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (15 May 2017). "Asteroid 2014 YX49: a large transient Trojan of Uranus". Monthly Notices of the Royal Astronomical Society. 467 (2): 1561–1568. arXiv:1701.05541. Bibcode:2017MNRAS.467.1561D. doi:10.1093/mnras/stx197.


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