|Discovered by||David C. Jewitt, Scott S. Sheppard and Jan Kleyna|
|Discovery date||9 December 2001|
|(148975) 2001 XA255|
|Epoch 13 January 2016 (JD 2457400.5)|
|Uncertainty parameter 2|
|Observation arc||3812 days (10.44 yr)|
|Aphelion||48.731 AU (7.2901 Tm)|
|Perihelion||9.3364 AU (1.39671 Tm)|
|29.034 AU (4.3434 Tm)|
|156.44 yr (57141.1 d)|
|0° 0m 22.681s / day|
|Jupiter MOID||4.12722 AU (617.423 Gm)|
(148975) 2001 XA255, provisional designation 2001 XA255, is a dark minor planet in the outer Solar System, classified as centaur, approximately 20 kilometers in diameter. The object is currently trapped in a 1:1 mean-motion resonance with Neptune following a path of the horseshoe type.
2001 XA255 follows a very eccentric orbit (0.68) with perihelion just inside the orbit of Saturn, aphelion in the trans-Neptunian belt and a semi-major axis of 28.9 AU. The orbital inclination of this object is moderate at 12.6º.
The object has an estimated diameter of 12.5 km and it was classified as an inactive centaur by David C. Jewitt. Observations by the NEOWISE mission gave a larger diameter of 37.7 kilometers and an albedo of 0.041. It has an absolute magnitude is 11.1.
2001 XA255 was identified as trapped in a 1:1 mean-motion resonance with Neptune and 1:2 with Uranus by T. Gallardo in 2006. The object is dynamically unstable and it entered the region of the giant planets relatively recently, perhaps 50,000 years ago, from the scattered disk. It follows a short-lived horseshoe orbit around Neptune.