2011 UB256

2011 UB₂₅₆
Discovery
Discovered by	Pan-STARRS
Discovery date	29 October 2011
Designations
MPC designation	2011 UB256
Minor planet category	Martian L5
Orbital characteristics
	Epoch 31 May 2020 (JD 2459000.5)
	Uncertainty parameter 0
Observation arc	6265 days (17.15 yr)
Aphelion	1.631894031 AU (244.1278722 Gm)
Perihelion	1.4154896 AU (211.75423 Gm)
Semi-major axis	1.523691798 AU (227.9410486 Gm)
Eccentricity	0.0710132
Orbital period (sidereal)	1.88 yr (686.980044 d)
Mean anomaly	180.60444°
Mean motion	0° 31m 26.518s /day
Inclination	24.30270°
Longitude of ascending node	58.781126°
Argument of perihelion	7.58178°
Earth MOID	0.428887 AU (64.1606 Gm)
Jupiter MOID	3.5641 AU (533.18 Gm)
Physical characteristics
Mean diameter	300 m
Geometric albedo	0.5-0.05 (assumed)
Absolute magnitude (H)	19.9

2011 UB₂₅₆ is a small asteroid and Mars trojan orbiting near the L₅ point of Mars (60 degrees behind Mars on its orbit).^[2]^[3]^[4]

Discovery, orbit and physical properties

2011 UB₂₅₆ was first observed on 29 October 2011 by the Pan-STARRS 1 telescope system at Haleakala; the Apache Point-Sloan Digital Sky Survey had imaged this object on 31 March 2003 without identifying it as an asteroid.^[5] Its orbit is characterized by low eccentricity (0.071), moderate inclination (24.3°) and a semi-major axis of 1.52 AU.^[5] Upon discovery, it was classified as Mars-crosser by the Minor Planet Center. Its orbit is well determined as it is currently (January 2021) based on 64 observations with a data-arc span of 6265 days.^[1] 2011 UB₂₅₆ has an absolute magnitude of 19.9 which gives a characteristic diameter of 300 m.^[1]

Mars trojan and orbital evolution

Recent calculations indicate that it is a stable L₅ Mars trojan.^[2] It may not be a member of the so-called Eureka family.

Mars trojan

L₄ (leading):

(121514) 1999 UJ7 †

L₅ (trailing):

References

^ ^a ^b ^c "JPL Small-Body Database Browser: (2011 UB256)". Jet Propulsion Laboratory. Retrieved 12 January 2021.
^ ^a ^b Christou, Apostolos A.; Borisov, Galin; Dell'Oro, Aldo; Jacobson, Seth A.; Cellino, Alberto; Unda-Sanzana, Eduardo (January 2020). "Population control of Mars Trojans by the Yarkovsky & YORP effects". Icarus. 335 (1): 113370 (34 pages). arXiv:1907.12858. Bibcode:2020Icar..33513370C. doi:10.1016/j.icarus.2019.07.004. S2CID 198985887.
^ Christou, Apostolos A.; Borisov, Galin; Dell'Oro, Aldo; Cellino, Alberto; Devogèle, Maxime (January 2021). "Composition and origin of L₅ Trojan asteroids of Mars: Insights from spectroscopy". Icarus. 354 (1): 113994 (22 pages). arXiv:2010.10947. Bibcode:2021Icar..35413994C. doi:10.1016/j.icarus.2020.113994. S2CID 224814529.
^ de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (March 2021). "Using Mars co-orbitals to estimate the importance of rotation-induced YORP break-up events in Earth co-orbital space". Monthly Notices of the Royal Astronomical Society. 501 (4): 6007–6025. arXiv:2101.02563. Bibcode:2021MNRAS.501.6007D. doi:10.1093/mnras/stab062.
^ ^a ^b MPC data on 2011 SP189

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 UB₂₅₆ data at MPC.
2011 UB256 at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
2011 UB256 at ESA–space situational awareness
- Ephemerides · Observations · Orbit · Physical properties · Summary
2011 UB256 at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

[jpl-1] "JPL Small-Body Database Browser: (2011 UB256)". Jet Propulsion Laboratory. Retrieved 12 January 2021.

[MTAchristou1-2] Christou, Apostolos A.; Borisov, Galin; Dell'Oro, Aldo; Jacobson, Seth A.; Cellino, Alberto; Unda-Sanzana, Eduardo (January 2020). "Population control of Mars Trojans by the Yarkovsky & YORP effects". Icarus. 335 (1): 113370 (34 pages). arXiv:1907.12858. Bibcode:2020Icar..33513370C. doi:10.1016/j.icarus.2019.07.004. S2CID 198985887.

[MTAchristou2-3] Christou, Apostolos A.; Borisov, Galin; Dell'Oro, Aldo; Cellino, Alberto; Devogèle, Maxime (January 2021). "Composition and origin of L₅ Trojan asteroids of Mars: Insights from spectroscopy". Icarus. 354 (1): 113994 (22 pages). arXiv:2010.10947. Bibcode:2021Icar..35413994C. doi:10.1016/j.icarus.2020.113994. S2CID 224814529.

[MTAmarcos-4] Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (March 2021). "Using Mars co-orbitals to estimate the importance of rotation-induced YORP break-up events in Earth co-orbital space". Monthly Notices of the Royal Astronomical Society. 501 (4): 6007–6025. arXiv:2101.02563. Bibcode:2021MNRAS.501.6007D. doi:10.1093/mnras/stab062.

[mpc-5] MPC data on 2011 SP189

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