2011 SL₂₅

Discovery
Discovered by	Alianza S4
Discovery site	Cerro Burek
Discovery date	21 September 2011
Designations
MPC designation	2011 SL25
Minor planet category	Martian L5
Orbital characteristics [1]
Epoch 13 January 2016 ( JD 2457400.5)
Uncertainty parameter 2
Observation arc	1637 days (4.48 yr)
Aphelion	1.698231  AU (254.0517  Gm)
Perihelion	1.349540 AU (201.8883 Gm)
Semi-major axis	1.523885 AU (227.9700 Gm)
Eccentricity	0.114409
Orbital period (sidereal)	1.88 yr (687.11 d)
Mean anomaly	55.63918 °
Mean motion	0° 31m 26.159s /day
Inclination	21.49603°
Longitude of ascending node	9.413048°
Argument of perihelion	53.31859°
Earth  MOID	0.396438 AU (59.3063 Gm)
Jupiter  MOID	3.52931 AU (527.977 Gm)
Physical characteristics
Mean diameter	550±230  m
Geometric albedo	0.5-0.05 (assumed)
Absolute magnitude (H)	19.4

2011 SL₂₅, also written as 2011 SL25, is an asteroid and Mars trojan candidate that shares the orbit of the planet Mars at its L₅ point. ^[2]

Discovery, orbit and physical properties

2011 SL₂₅ was discovered on 21 September 2011 at the Alianza S4 Observatory ( I08) on Cerro Burek in Argentina ^[3] and classified as Mars-crosser by the Minor Planet Center. It follows a relatively eccentric orbit (0.11) with a semi-major axis of 1.52 AU. ^[3] This object has noticeable orbital inclination (21.5°). ^[3] Its orbit was initially poorly constrained, with only 76 observations over 42 days, but was recovered in January 2014. ^[1] 2011 SL₂₅ has an absolute magnitude of 19.5 which gives a characteristic diameter of 575 m. ^[1]

Mars trojan and orbital evolution

Recent calculations indicate that it is a stable L₅ Mars Trojan with a libration period of 1400 yr and an amplitude of 18°. ^{[2] [4]} values as well as its short-term orbital evolution are similar to those of 5261 Eureka. ^{[5] [6]}

Origin

Long-term numerical integrations show that its orbit is stable on Gyr time-scales (1 Gyr = 1 billion years). It appears to be stable at least for 4.5 Gyr but its current orbit indicates that it has not been a dynamical companion to Mars for the entire history of the Solar System. ^[2]

See also

• 5261 Eureka (1990 MB)
• (101429) 1998 VF31
• (121514) 1999 UJ7
• (311999) 2007 NS2
• (385250) 2001 DH47
• 2009 SE
• 2011 SC191
• 2011 SP189
• 2011 UB256
• 2011 UN63
• 2016 CP31
• 2018 EC4
• 2018 FC4
• 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 SL₂₅ data at MPC.
• 2011 SL25 at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 2011 SL25 at ESA– space situational awareness
  • Ephemerides · Observations · Orbit · Physical properties · Summary
• 2011 SL25 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters