(315530) 2008 AP129

(315530) 2008 AP₁₂₉ (provisional designation 2008 AP₁₂₉) is a trans-Neptunian object and possibly a cubewano from the outermost regions of the Solar System, approximately 480 kilometers in diameter. It was discovered on 11 January 2008, by American Michael E. Brown and Megan Schwamb at Palomar Observatory in California.^[4]

(315530) 2008 AP₁₂₉

Discovery[1]
Discovered by	M. E. Schwamb M. E. Brown
Discovery site	Palomar Obs.
Discovery date	11 January 2008
Designations
MPC designation	(315530) 2008 AP129
Alternative designations	2008 AP129
Minor planet category	TNO[1] · cubewano(?)[2] Extended[3] · distant[4]
Orbital characteristics[1]
Epoch 2 February 2023 (JD 2460000.5)
Uncertainty parameter 2
Observation arc	33.46 yr (12,220 days)
Earliest precovery date	9 October 1989
Aphelion	47.503 AU
Perihelion	35.837 AU
Semi-major axis	41.670 AU
Eccentricity	0.1400
Orbital period (sidereal)	268.99 yr (98,249 d)
Mean anomaly	57.045°
Mean motion	0° 0m 13.32s / day
Inclination	27.458°
Longitude of ascending node	14.757°
Argument of perihelion	56.567°
Physical characteristics
Dimensions	460.81 km (calculated)[5] 486 km[2] 494 km[6]
Synodic rotation period	9.04±0.02 h[7]
Geometric albedo	0.07 (assumed)[6] 0.09 (assumed)[2] 0.10 (assumed)[5]
Spectral type	C (assumed)[5]
Absolute magnitude (H)	4.95[1][5] · 5.1[6]

Description

2008 AP₁₂₉ orbits the Sun at a distance of 35.8–47.5 AU once every 267 years and 11 months (98,249 days; semi-major axis of 41.70 AU). Its orbit has an eccentricity of 0.14 and an inclination of 27° with respect to the ecliptic.^[1] It has 3 precovery observations back to 1989.^[4] Lightcurve analysis gave an ambiguous rotation period of 9.04 hours with a brightness amplitude of 0.12 magnitude (U=2).^[5][7] 2008 AP₁₂₉ has been identified as a member of the Haumea family in a dynamical study led by Proudfoot and Ragozzine in 2019.^[8]

Origin

Main article: Haumea family

Based on their common pattern of infrared water-ice absorption and the clustering of their orbital elements, the other KBOs, it appear to be collisional fragments broken off the dwarf planet Haumea. The neutral color of the spectrum of these objects in the visible range evidences a lack of complex organics on the surface of these bodies that has been studied in detail for the surface of Haumea.^{[citation needed]}

Numbering and naming

This minor planet was numbered by the Minor Planet Center on 7 February 2012.^[9] As of 2025, it has not been named.^[4]