astro.wikisort.org - Asteroid

2011 SP₁₈₉ is a small asteroid and Mars trojan orbiting near the L₅ point of Mars (60 degrees behind Mars on its orbit).[2][3][4]

2011 SP₁₈₉

Discovery
Discovered by	Mt. Lemmon Survey
Discovery date	29 September 2011
Designations
MPC designation	2011 SP189
Minor planet category	Martian L5
Orbital characteristics[1]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc	2390 days (6.54 yr)
Aphelion	1.5852549 AU (237.15076 Gm)
Perihelion	1.462275 AU (218.7532 Gm)
Semi-major axis	1.5237649 AU (227.95198 Gm)
Eccentricity	0.040354
Orbital period (sidereal)	1.88 yr (687.0295 d)
Mean anomaly	110.302°
Mean motion	0° 31m 26.382s /day
Inclination	19.89778°
Longitude of ascending node	0.663826°
Argument of perihelion	122.545°
Earth MOID	0.490971 AU (73.4482 Gm)
Jupiter MOID	3.40399 AU (509.230 Gm)
Physical characteristics
Mean diameter	300 m
Geometric albedo	0.5-0.05 (assumed)
Absolute magnitude (H)	20.9

Discovery, orbit and physical properties

2011 SP₁₈₉ was first observed on 29 September 2011 by the Mount Lemmon Survey.[5] Its orbit is characterized by low eccentricity (0.040), moderate inclination (19.9°) 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 45 observations with a data-arc span of 2390 days.[1] 2011 SP₁₈₉ has an absolute magnitude of 20.9 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 with a libration period of 1300 yr and an amplitude of 20°.[2] These values are similar to those of 5261 Eureka and related objects and it may be a member of the so-called Eureka family.

Mars trojan

L₄ (leading):

• (121514) 1999 UJ7 †

L₅ (trailing):

• 5261 Eureka (1990 MB) †
• (101429) 1998 VF31 †
• (311999) 2007 NS2 †
• (385250) 2001 DH47
• 2009 SE
• 2011 SC191
• 2011 SL25
• 2011 SP189
• 2011 UB256
• 2011 UN63
• 2016 CP31
• 2018 EC4
• 2018 FC4

See also

• 2020 VT1

References

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 SP₁₈₉ data at MPC.
• 2011 SP189 at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 2011 SP189 at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical Properties · Summary
• 2011 SP189 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

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