2011 UN63

2011 UN₆₃

Discovery
Discovered by	Mt. Lemmon Survey
Discovery date	October 21, 2011
Designations
MPC designation	2011 UN63
Minor planet category	Martian L5
Orbital characteristics[1]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 1
Observation arc	1587 days (4.34 yr)
Aphelion	1.6222522 AU (242.68547 Gm)
Perihelion	1.4253677 AU (213.23197 Gm)
Semi-major axis	1.5238099 AU (227.95872 Gm)
Eccentricity	0.0646027
Orbital period	1.88 yr (687.06 d)
Mean anomaly	101.29418°
Mean motion	0° 31^m 26.298^s /day
Inclination	20.36086°
Longitude of ascending node	223.55542°
Argument of perihelion	165.28918°
Earth MOID	0.434823 AU (65.0486 Gm)
Jupiter MOID	3.54877 AU (530.888 Gm)
Physical characteristics
Dimensions	560 m
Geometric albedo	0.5-0.05 (assumed)
Absolute magnitude (H)	19.7

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

Discovery, orbit and physical properties

2011 UN₆₃ was first observed on September 27, 2009 by the Mt. Lemmon Survey and given the provisional designation 2009 SA₁₇₀. Lost, it was re-discovered on October 21, 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]

Mars trojan and orbital evolution

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.

Origin

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]

See also

• 5261 Eureka
• 1999 UJ7
• 1998 VF31
• 2001 DH47
• 2007 NS2
• 2011 SC191
• 2011 SL25

References

1. "JPL Small-Body Database Browser: (2011 UN63)". Jet Propulsion Laboratory. Retrieved 31 March 2016.
2. de la Fuente Marcos, C.; de la Fuente Marcos, R. (April 2013). "Three new stable L5 Mars Trojans". Monthly Notices of the Royal Astronomical Society: Letters. 432 (1): L31–L35. arXiv:1303.0124. Bibcode:2013MNRAS.432L..31D. doi:10.1093/mnrasl/slt028.
3. Christou, A. A. (2013). "Orbital clustering of Martian Trojans: An asteroid family in the inner solar system?". Icarus. 224 (1): 144–153. arXiv:1303.0420. Bibcode:2013Icar..224..144C. doi:10.1016/j.icarus.2013.02.013.
4. MPC data on 2011 UN63

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.

External links

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