2011 UN63

2011 UN₆₃, also written as 2011 UN63, is a Mars trojan, an asteroid orbiting near the L₅ point of Mars (60 degrees behind Mars on its orbit).^[2][3]

2011 UN₆₃ was first observed on 27 September 2009 by the Mt. Lemmon Survey and given the provisional designation 2009 SA₁₇₀. Lost, it was re-discovered on 21 October 2011 again by the Mt. Lemmon Survey.^[4] 2011 UN₆₃ follows a low eccentricity orbit (0.064) with a semi-major axis of 1.52 AU.^[4] This object has moderate orbital inclination (20.4°).^[4] It was classified as Mars-crosser by the Minor Planet Center upon discovery. Its orbit is relatively well determined as it is currently (March 2013) based on 64 observations with a data-arc span of 793 days.^[1] This asteroid has an absolute magnitude of 19.7 which gives a characteristic diameter of 560 m.^[1]

Recent calculations^[2][3] indicate that it is a stable L₅ Mars trojan asteroid with a libration period of 1350 yr and an amplitude of 14°. These values as well as its short-term orbital evolution are similar to those of 5261 Eureka or 2011 SC191.

Long-term numerical integrations show that its orbit is very stable on Gyr time-scales (1 Gyr = 1 billion years). As in the case of Eureka, calculations in both directions of time (4.5 Gyr into the past and 4.5 Gyr into the future) indicate that 2011 UN₆₃ may be a primordial object, perhaps a survivor of the planetesimal population that formed in the terrestrial planets region early in the history of the Solar System.^[2]

• 5261 Eureka (1990 MB)
• (101429) 1998 VF31
• (121514) 1999 UJ7
• (311999) 2007 NS2
• (385250) 2001 DH47
• 2009 SE
• 2011 SC191
• 2011 SL25
• 2011 SP189
• 2011 UB256
• 2016 CP31
• 2018 EC4
• 2018 FC4
• 2020 VT1

Further reading

• Three new stable L5 Mars Trojans de la Fuente Marcos, C., de la Fuente Marcos, R. 2013, Monthly Notices of the Royal Astronomical Society: Letters, Vol. 432, Issue 1, pp. 31–35.
• Orbital clustering of Martian Trojans: An asteroid family in the inner solar system? Christou, A. A. 2013, Icarus, Vol. 224, Issue 1, pp. 144–153.

• 2011 UN₆₃ data at MPC
• 2011 UN₆₃ data at AstDyS-2.
• 2011 UN63 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters