Discovered by Sheppard & Trujillo Observation arc 380 days (1.04 yr) Semi-major axis 29.969 AU (4.4833 Tm) Orbital period 164 years Inclination 27.546° Asteroid group Neptune trojan | Discovery date 2008-06-07 Aphelion 32.458 AU (4.8556 Tm) Eccentricity 0.083041 Discovered 7 June 2008 Argument of perihelion 8.1692° | |
Discoverers Chad Trujillo, Scott S. Sheppard Similar Psamathe, (316179) 2010 EN65, S/2004 N 1, Sao, Laomedeia | ||
2008 lc18
2008 LC18 is a Neptune trojan discovered on June 7, 2008, by Scott S. Sheppard and Chad Trujillo using the Subaru telescope. It was the seventh such object to be discovered, as well as the first to be found in the region of the trailing L5 Lagrangian point about 60 degrees behind Neptune. Like all Neptune trojans, 2008 LC18 has the same orbital period as Neptune; i.e. it and Neptune are in a 1:1 orbital resonance.
2008 LC18 has an inclination of 27.5 degrees. As of August 2010, this is the second highest inclination of any known Neptune trojan.
With an absolute magnitude of 8.4, it has a diameter estimated at ~100 km.
The search for L5 trojans of Neptune has been impeded by the fact that this region of space is currently along the line of sight to the center of the Milky Way, an area of the sky crowded with stars. 2008 LC18 was found in a location where background stars are obscured by a dust cloud. The discovery of one Neptune L5 trojan in a searched area of 19 square degrees suggests that there may be 150 Neptune L5 trojans with a diameter greater than ~80 km (24th magnitude), similar to the estimate of such objects in Neptune's L4 swarm.
2008 LC18 was not close enough for investigation by the New Horizons spacecraft when it crossed Neptune's L5 region en route to Pluto in 2013–2014, but its discovery showed that other, more accessible Neptune trojans could potentially have been found before that time. 2008 LC18 was 2 AU from Pluto in 1997. 2008 LC18 crossed the ecliptic plane in 2011. As of 2016, it is 33 AU from Neptune.