2015 RR245 is a Dwarf Planet in a 9:2 Orbital Resonance

2015 RR245 is a dwarf planet candidate detected by the Outer Solar System Origins Survey (OSSOS). It is in an eccentric orbit around the Sun. 2015 RR245 comes as close as 34 AU to the Sun and recedes as far as 130 AU from the Sun. If the albedo of 2015 RR245 is assumed to be 12 percent, then 2015 RR245 should have a diameter of approximately 670 km. 2015 RR245 is trapped in a 9:2 mean-motion resonance with Neptune and it is the first known Trans-Neptunian Object (TNO) to be in this orbital resonance.

Reference:
Bannister et al. (2016), "OSSOS: IV. Discovery of a dwarf planet candidate in the 9:2 resonance", arXiv:1607.06970 [astro-ph.EP]