|Discovery site||Mauna Kea Obs.|
|Discovery date||24 May 2004|
|MPC designation||2004 KV18|
|Neptune trojan · L5 
TNO  · distant 
|Orbital characteristics |
|Epoch 4 September 2017 (JD 2458000.5)|
|Uncertainty parameter 4|
|Observation arc||1.94 yr (708 days)|
|167.37 yr (61,132 days)|
|0° 0m 21.24s / day|
|Dimensions||56 km (assumed)
71 km (est. at 0.10)
2004 KV18 is an eccentric Neptune trojan trailering Neptune's orbit in the outer Solar System, approximately 70 kilometers in diameter. It was first observed on 24 May 2004, by astronomers at the Mauna Kea Observatories on Hawaii, United States. It was the eighth Neptune trojan identified and the second in Neptune's L5 Lagrangian point.
Orbit and classification
Neptune trojans are resonant trans-Neptunian objects (TNO) in a 1:1 mean-motion orbital resonance with Neptune. These Trojans have a semi-major axis and an orbital period very similar to Neptune's (30.10 AU; 164.8 years).
2004 KV18 belongs to the trailing L5 group, which follow 60° behind Neptune's orbit. It orbits the Sun with a semi-major axis of 30.370 AU at a distance of 24.7–36.1 AU once every 167 years and 4 months (61,132 days). Its orbit has a notably high eccentricity of 0.19 and an inclination of 14° with respect to the ecliptic.
2004 KV18 is not a primordial Neptune trojan, and will leave the region on a relatively short time scale. The orbit of a Neptune trojan can only be stable when the eccentricity is less than 0.12.:6 Its lifetime as a trailing Neptune trojan is on the order of 100,000 years into the future.
Diameter and albedo
Based on a generic magnitude-to-diameter conversion, it measures approximately 71 kilometers in diameter using an absolute magnitude of 8.9 and an assumed albedo of 0.10. It is one of the smaller bodies among the first 17 Neptune trojans discovered so far, which measure between 60 and 200 kilometers (for an absolute magnitude of 9.3–6.6 and an assumed albedo of 0.10). Other estimates, implying a higher albedo than 0.10, gave a diameter of approximately 56 kilometers.
Numbering and naming
Due to its orbital uncertainty, this minor planet has not been numbered and its official discoverers have not been determined. If named, it will follow the naming scheme already established with 385571 Otrera, which is to name these objects after figures related to the Amazons, an all-female warrior tribe that fought in the Trojan War on the side of the Trojans against the Greek.
- "JPL Small-Body Database Browser: (2004 KV18)" (2006-05-02 last obs.). Jet Propulsion Laboratory. Retrieved 4 August 2017.
- "2004 KV18". Minor Planet Center. Retrieved 4 August 2017.
- "List Of Neptune Trojans". Minor Planet Center. 10 July 2017. Retrieved 4 August 2017.
- "2004 KV18". The Tracking News – Observations of small Solar-System bodies. Retrieved 4 August 2017.
- "Asteroid Size Estimator". CNEOS/JPL. Retrieved 4 August 2017.
- Guan, Pu; Zhou, Li-Yong; Li, Jian (November 2012). "Trailing (L5) Neptune Trojans: 2004 KV18 and 2008 LC18" (PDF). Research in Astronomy and Astrophysics. 12 (11): 1549–1562. Bibcode:2012RAA....12.1549G. arXiv: . doi:10.1088/1674-4527/12/11/009. Retrieved 4 August 2017.
- Zhou, Li-Yong; Dvorak, Rudolf; Sun, Yi-Sui (September 2009). "The dynamics of Neptune Trojan - I. The inclined orbits" (PDF). Monthly Notices of the Royal Astronomical Society. 398 (3): 1217–1227. Bibcode:2009MNRAS.398.1217Z. arXiv: . doi:10.1111/j.1365-2966.2009.15203.x. Retrieved 4 August 2017.