2011 SC191

2011 SC₁₉₁

Discovery
Discovered by	Mt. Lemmon Survey
Discovery date	October 31, 2011
Designations
MPC designation	2011 SC191
Minor planet category	Martian L5
Orbital characteristics[1]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 0
Observation arc	4715 days (12.91 yr)
Aphelion	1.5910690 AU (238.02053 Gm)
Perihelion	1.4565161 AU (217.89171 Gm)
Semi-major axis	1.5237925 AU (227.95611 Gm)
Eccentricity	0.0441507
Orbital period	1.88 yr (687.05 d)
Mean anomaly	273.27420°
Mean motion	0° 31m 26.331s /day
Inclination	18.74554°
Longitude of ascending node	5.780691°
Argument of perihelion	196.33006°
Earth MOID	0.459583 AU (68.7526 Gm)
Jupiter MOID	3.37018 AU (504.172 Gm)
Physical characteristics
Dimensions	600 m
Geometric albedo	0.5-0.05 (assumed)
Absolute magnitude (H)	19.3

2011 SC₁₉₁, also written as 2011 SC191, is a small asteroid orbiting near the L₅ point of Mars (60 degrees behind Mars on its orbit).^[2][3]

Discovery, orbit and physical properties

2011 SC₁₉₁ was first observed on March 21, 2003 by the Near-Earth Asteroid Tracking (NEAT) project at Palomar Observatory using the Samuel Oschin telescope and given the provisional designation 2003 GX₂₀. The object was subsequently lost and re-discovered on October 31, 2011 by the Mt. Lemmon Survey.^[4][5] Its orbit is characterized by low eccentricity (0.044), moderate inclination (18.7°) 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 (March 2013) based on 45 observations with a data-arc span of 3,146 days.^[1] 2011 SC₁₉₁ has an absolute magnitude of 19.3 which gives a characteristic diameter of 600 m.^[1]

Mars trojan and orbital evolution

Recent calculations indicate that it is a stable L₅ Mars trojan with a libration period of 1300 yr and an amplitude of 18°.^[2][3] These values as well as its short-term orbital evolution are similar to those of 5261 Eureka. Its eccentricity oscillates mainly due to secular resonances with the Earth and the oscillation in inclination is likely driven by secular resonances with Jupiter.^[2]

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 SC₁₉₁ 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 SL25
• 2011 UN63

References

Further reading

• 2011 SC191 Pettarin, E., Vivona, M., McMillan, R. S., Pietschnig, M., Klein, M., Boattini, A., Gibbs, A. R., Ahern, J. D., Beshore, E. C., Garradd, G. J., Grauer, A. D., Hill, R. E., Kowalski, R. A., Larson, S. M., McNaught, R. H., Birtwhistle, P. 2011, Minor Planet Electronic Circular, 2011-T02.
• 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 SC₁₉₁ data at MPC.
• 2011 SC₁₉₁ data at AstDyS-2.
• 2011 SC191 at the JPL Small-Body Database
  • Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters