2005 RH52

2005 RH₅₂ is an extreme trans-Neptunian object from the extended scattered disc in the outermost region of the Solar System, approximately 130 kilometers (81 miles) in diameter. It was first observed on 3 September 2005, by astronomers with the Canada–France Ecliptic Plane Survey using the Canada–France–Hawaii Telescope at the Mauna Kea Observatories in Hawaii, United States.^[1][2][3]

2005 RH₅₂

Discovery[1][2][3]
Discovered by	(first observed only) CFEPS
Discovery site	Mauna Kea Obs.
Discovery date	3 September 2005
Designations
MPC designation	2005 RH52
Minor planet category	TNO[4] · ESDO[5] ETNO · distant[1]
Orbital characteristics[4]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 3
Observation arc	12.30 yr (4,491 d)
Aphelion	270.41 AU
Perihelion	38.956 AU
Semi-major axis	154.68 AU
Eccentricity	0.7482
Orbital period (sidereal)	1924 yr (702,689 d)
Mean anomaly	2.9912°
Mean motion	0° 0m 1.8s / day
Inclination	20.428°
Longitude of ascending node	306.01°
Argument of perihelion	32.366°
Neptune MOID	10.2 AU[1]
Physical characteristics
Mean diameter	128 km (est.)[5] 130 km (est.)[6]
Geometric albedo	0.08 (assumed)[6] 0.09 (assumed)[5]
Absolute magnitude (H)	7.7[1][4]

The detached, extended scattered disc object (ESDO) is on a highly eccentric orbit and belongs to the extreme trans-Neptunian objects.

Orbit and classification

2005 RH₅₂ belongs to a small group of detached objects with perihelion distances of 30 AU or more, and semi-major axes of 150 AU or more.^[7] Such extreme trans-Neptunian objects (ETNOs) can not reach such orbits without some perturbing object, which leads to the speculation of Planet Nine.

It orbits the Sun at a distance of 39–270 AU once every 1923 years and 10 months (702,689 days; semi-major axis of 154.68 AU). Its orbit has an eccentricity of 0.75 and an inclination of 20° with respect to the ecliptic.^[4] The body's observation arc begins with its first official observation at Mauna Kea in September 2005.^[1]

Numbering and naming

As of 2025, this minor planet has neither been numbered nor named by the Minor Planet Center. The official discoverer(s) will be defined when the object is numbered.^[1]

Physical characteristics

According to Johnston's archive and to American astronomer Michael Brown, 2005 RH₅₂ measures 128 and 130 kilometers in diameter based on an assumed albedo of 0.09 and 0.08, respectively.^[5][6] Due to its small size, it is listed as "probably not" a dwarf planet (100–200 km) on Michael Brown's website, which uses a 5-class taxonomic system that ranges from "nearly certainly" to "possibly" for potential dwarf planet candidates.^[6] As of 2018, no rotational lightcurve has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.^[4][8]

See also

• List of unnumbered trans-Neptunian objects § 2005 RH52