The Mars trojans are a group of trojan objects that share the orbit of the planet Mars around the Sun. They can be found around the two Lagrangian points 60° ahead of and behind Mars. The origin of the Mars trojans is not well understood. One theory suggests that they were primordial objects left over from the formation of Mars that were captured in its Lagrangian points as the Solar System was forming. However, spectral studies of the Mars trojans indicate this may not be the case.[1][2] Another explanation involves asteroids chaotically wandering into the Mars Lagrangian points later in the Solar System's formation. This is also questionable considering the short dynamical lifetimes of these objects.[3][4] The spectra of Eureka and two other Mars trojans indicates an olivine-rich composition.[5] Since olivine-rich objects are rare in the asteroid belt it has been suggested that some of the Mars trojans are captured debris from a large orbit-altering impact on Mars when it encountered a planetary embryo.[6][3]
Presently, this group contains 17 asteroids confirmed to be stable Mars trojans by long-term numerical simulations but only nine of them are accepted by the Minor Planet Center.[7][3][4][8][9][10][11]
Due to close orbital similarities, most of the smaller members of the L5 group are hypothesized to be fragments of Eureka that were detached after it was spun up by the YORP effect (Eureka's rotational period is 2.69 h). The L4 trojan 1999 UJ7 has a much longer rotational period of ~50 h, apparently due to a chaotic rotation that prevents YORP spinup.[12] The spectrum of 121514 show a certain resemblance to that of 2023 FW14 and a common origin cannot be discarded.[13] The spectra of 121514 and 2023 FW14 are very different from those of the Eureka asteroid family members.
| Designation | Cloud | Semimajor axis (AU) |
Perihelion (AU) |
Eccentricity | Inclination (°) |
(H) | Diameter (m) |
|---|---|---|---|---|---|---|---|
| 5261 Eureka | L5 | 1.52356 | 1.42477 | 0.06484 | 20.2820 | 16.13 | 1880±230 |
| (101429) 1998 VF31 | L5 | 1.52429 | 1.37150 | 0.10024 | 31.2987 | 17.26 | 1210+890 −350 |
| (121514) 1999 UJ7 | L4 | 1.52455 | 1.46491 | 0.03912 | 16.7493 | 17.19 | 2450±490 |
| (311999) 2007 NS2 | L5 | 1.52379 | 1.44155 | 0.05397 | 18.6194 | 18.18 | 790+580 −230 |
| (385250) 2001 DH47 | L5 | 1.52385 | 1.47111 | 0.03461 | 24.4006 | 18.89 | 570+420 −170 |
| 2009 SE | L5 | 1.52451 | 1.42524 | 0.06512 | 20.6263 | 19.9 | 360+260 −110 |
| 2011 SL25 | L5 | 1.52391 | 1.34938 | 0.11453 | 21.4953 | 19.5 | 430+320 −120 |
| 2011 SP189 | L5 | 1.52386 | 1.46247 | 0.04029 | 19.8994 | 20.9 | 230+160 −70 |
| 2011 SC191 | L5 | 1.52390 | 1.45678 | 0.04405 | 18.7451 | 19.4 | 450+330 −130 |
| 2011 UN63 | L5 | 1.52378 | 1.42521 | 0.06469 | 20.3635 | 19.7 | 390+290 −110 |
| 2011 UB256 | L5 | 1.52370 | 1.41550 | 0.07101 | 24.3023 | 19.9 | 360+260 −110 |
| 2016 AA165 | L5 | 1.52299 | 1.38650 | 0.08962 | 18.7202 | 20.39 | 290+210 −90 |
| 2016 CP31 | L5 | 1.52365 | 1.43425 | 0.05867 | 23.1314 | 19.4 | 450+330 −130 |
| 2018 EC4 | L5 | 1.52365 | 1.43138 | 0.06056 | 21.8362 | 20.0 | 340+250 −100 |
| 2018 FC4 | L5 | 1.52388 | 1.49781 | 0.01711 | 22.1466 | 21.2 | 200+140 −60 |
| 2018 FM29 | L5 | 1.52391 | 1.45196 | 0.04722 | 21.5004 | 21.11 | 210+150 −60 |
| 2023 FW14 | L4 | 1.52377 | 1.28284 | 0.15811 | 13.27271 | 21.59 | 318+493 −199 |
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