(309239) 2007 RW10

Lore & Background

2007 RW10 was discovered by the Palomar Distant Solar System Survey on September 9, 2007, with precovery images from 1988 also taken at Palomar. At discovery, it was believed to be a Neptune trojan, but it is no longer listed as such. The Jet Propulsion Laboratory classifies it as a trans-Neptunian object, while the Minor Planet Center includes it among centaurs. Herschel-PACS observations indicate a diameter of 247 km.

It currently follows a quasi-satellite loop around Neptune, having been in that state for about 12,500 years and remaining for another 12,500 years. Prior to this, it was an L5 trojan, and it will return to that state after leaving its quasi-satellite orbit. Its orbital inclination of 36.2° is the largest among known Neptune co-orbitals.

2007 RW10 is a dynamically hot object (high eccentricity and inclination) unlikely to be a primordial Neptune co-orbital. It probably originated well beyond Neptune and was later temporarily captured in the 1:1 resonance with Neptune.

Reader's Guide

2007 RW10 is significant as a temporary quasi-satellite of Neptune, a dynamical state in which it appears to revolve around Neptune over one Neptunian year while actually orbiting the Sun. Its classification is disputed: the Jet Propulsion Laboratory lists it as a trans-Neptunian object, while the Minor Planet Center categorizes it as a centaur. It holds the record for the largest orbital inclination among known Neptune co-orbitals and is possibly the largest known object trapped in a 1:1 mean-motion resonance with any major planet. Its dynamical history includes a past as an L5 trojan and a future return to that state after its current quasi-satellite phase, which spans about 12,500 years each way. The object is dynamically hot, suggesting it originated beyond Neptune and was temporarily captured, rather than being a primordial co-orbital. Its legacy lies in illustrating the complex co-orbital dynamics of trans-Neptunian objects and the temporary nature of such resonances.

Did You Know?

• 2007 RW10 has been a quasi-satellite of Neptune for about 12,500 years and will remain so for another 12,500 years.
• Prior to its quasi-satellite state, it was an L5 trojan of Neptune.