(506479) 2003 HB57

(506479) 2003 HB₅₇, is an extreme trans-Neptunian object of the extended scattered disc in the outermost region of the Solar System, approximately 180 kilometers in diameter. It was discovered by astronomers at the Mauna Kea Observatory on 26 April 2003.^[4]

(506479) 2003 HB₅₇

Discovery[1]
Discovered by	Mauna Kea Obs.
Discovery site	Mauna Kea Obs.
Discovery date	26 April 2003
Designations
MPC designation	(506479) 2003 HB57
Alternative designations	2003 HB57
Minor planet category	TNO[1] · E-SDO[2][3] distant[4] · detached
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 4
Observation arc	13.94 yr (5,090 days)
Aphelion	294.21 AU
Perihelion	38.109 AU
Semi-major axis	166.16 AU
Eccentricity	0.7706
Orbital period (sidereal)	2141.87 yr (782,317 days)
Mean anomaly	1.4255°
Mean motion	0° 0m 1.8s / day
Inclination	15.473°
Longitude of ascending node	197.82°
Argument of perihelion	11.013°
Physical characteristics
Mean diameter	147 km[2] 200 km[5]
Geometric albedo	0.04[5] 0.09[2]
Spectral type	BR[2]
Absolute magnitude (H)	7.4[1] · 7.6[5]

Description

2003 HB₅₇ orbits the Sun at a distance of 38.1–294.2 AU once every 2141 years and 10 months (782,317 days). Its orbit has an eccentricity of 0.77 and an inclination of 15° with respect to the ecliptic.^[1]

Extended scattered disc

It is one of a small group of extreme trans-Neptunian objects with perihelion distances of 30 AU or more, and semi-major axes of 150 AU or more.^[6] Such objects can not have reached their present-day orbits without the gravitational influence of some perturbing object, which leads to the speculation of Planet Nine.^[7][8]

Physical characterization

2003 HB₅₇ has a BR-type spectrum and an estimated diameter of 147 and 200 kilometers based on an assumed albedo of 0.09 and 0.04, respectively.^[2][5]