(309239) 2007 RW10

(309239) 2007 RW₁₀ (provisional designation 2007 RW₁₀) is a temporary quasi-satellite of Neptune.^[3] Observed from Neptune, it would appear to revolve around it over one Neptunian year but in reality, it orbits the Sun, not Neptune.

(309239) 2007 RW₁₀

Discovery
Discovered by	PDSSS
Discovery date	9 September 2007
Designations
Minor planet category	TNO[1] · Nept. co-orbital centaur · distant
Orbital characteristics[1]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 2
Observation arc	10693 days (29.28 yr)
Aphelion	39.28320 AU (5.876683 Tm)
Perihelion	21.06436 AU (3.151183 Tm)
Semi-major axis	30.17878 AU (4.514681 Tm)
Eccentricity	0.30201
Orbital period (sidereal)	165.79 yr (60555.1 d)
Mean anomaly	71.52911°
Mean motion	0° 0m 21.402s / day
Inclination	36.15744°
Longitude of ascending node	187.06355°
Argument of perihelion	95.64947°
Earth MOID	20.2499 AU (3.02934 Tm)
Jupiter MOID	17.1323 AU (2.56296 Tm)
TJupiter	3.880
Physical characteristics
Dimensions	247±30 km[2]
Geometric albedo	0.083+0.068 −0.039[2]
Absolute magnitude (H)	6.6[1]

Discovery, orbit and physical properties

2007 RW₁₀ was discovered by the Palomar Distant Solar System Survey on September 9, 2007,^[4][5] with precovery images from 1988 (also taken at Palomar).^[6] At the time of discovery, this minor body was believed to be a Neptune trojan,^[7] but it is no longer listed as such.^[8][9] The Jet Propulsion Laboratory classifies 2007 RW₁₀ as trans-Neptunian object but the Minor Planet Center includes the object among centaurs. It moves in an orbit with an inclination of 36.2°, a semi-major axis of 30.18 AU, and an eccentricity of 0.3020.^[1] Herschel-PACS observations indicate that it has a diameter of 247 km.^[2]

Quasi-satellite dynamical state and orbital evolution

2007 RW₁₀ is currently following a quasi-satellite loop around Neptune.^[3] It has been a quasi-satellite of Neptune for about 12,500 years and it will remain in that dynamical state for around another 12,500 years.^[3] Prior to the quasi-satellite dynamical state, 2007 RW₁₀ was an L₅ trojan and it will return to this state soon after leaving its current quasi-satellite orbit. Its orbital inclination is the largest among known Neptune co-orbitals. It is also possibly the largest known object trapped in the 1:1 mean-motion resonance with any major planet.

Origin

2007 RW₁₀ is a dynamically hot (both high eccentricity and inclination) object that is 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.^[3][10]

See also

• 2005 TN74, which was also suspected of being a Neptune trojan at the time of discovery