2015 KQ174
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2015 KQ174 orbits the Sun at a distance of 49.3–61.5 AU once every 412 years and 4 months (150,600 days; semi-major axis of 55.4 AU). Its orbit has an eccentricity of 0.11 and an inclination of 24° with respect to the ecliptic.[2]
The object belongs to the same group as 2004 XR190 ("Buffy"), 2014 FC72, 2014 FZ71 and 2015 FJ345 (also see diagram). With an orbital period of 412 years, it seems to be a resonant trans-Neptunian objects in a 2:5 resonance with Neptune,[7]: 12 as several other objects,[5] but with a lower eccentricity (0.11 instead of more than 0.60) and higher perihelia (at 49.3 AU rather than 31–41 AU).
Considered both a scattered and detached object,[3][4][5] 2015 KQ174 is particularly unusual as it has an unusually circular orbit for a scattered-disc object (SDO). Although it is thought that traditional scattered-disc objects have been ejected into their current orbits by gravitational interactions with Neptune, the low eccentricity of its orbit and the distance of its perihelion (SDOs generally have highly eccentric orbits and perihelia less than 38 AU) seems hard to reconcile with such celestial mechanics. This has led to some uncertainty as to the current theoretical understanding of the outer Solar System. The theories include close stellar passages, unseen planet/rogue planets/planetary embryos in the early Kuiper belt, and resonance interaction with an outward-migrating Neptune. The Kozai mechanism is capable of transferring orbital eccentricity to a higher inclination.[8][7] It is in a 5:2 resonance to Neptune. It seems to belong to the same group as 2004 XR190, nicknamed "Buffy".