(455502) 2003 UZ413

(455502) 2003 UZ₄₁₃ (provisional designation 2003 UZ₄₁₃) is a trans-Neptunian object (TNO) with an absolute magnitude of 4.38.^[5] It is in a 2:3 orbital resonance with Neptune, thus it is classified as a plutino.^[3] There are indications it may be dense enough to be a dwarf planet. It was given the minor planet number 455502 on 22 February 2016.^[11]

2003 UZ₄₁₃

Hubble Space Telescope image of 2003 UZ413 taken in 2008
Discovery[1]
Discovered by	M. E. Brown D. L. Rabinowitz C. A. Trujillo
Discovery date	21 October 2003
Designations
MPC designation	2003 UZ413
Minor planet category	TNO[2] · plutino[3][4][a]
Orbital characteristics[2]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 2
Observation arc	63.25 years (23103 days)\
Earliest precovery date	29 July 1954
Aphelion	47.968 AU (7.1759 Tm)
Perihelion	30.241 AU (4.5240 Tm)
Semi-major axis	39.104 AU (5.8499 Tm)
Eccentricity	0.22667
Orbital period (sidereal)	244.54 yr (89317.3 d)
Mean anomaly	113.43°
Mean motion	0° 0m 14.51s / day
Inclination	12.04911°
Longitude of ascending node	135.930°
Argument of perihelion	145.00°
Physical characteristics
Dimensions	650+1 −175 km (upper limit)[5] 472+122 −25 km (lower limit)[5]
Mass	≈3×1020 kg[b]
Mean density	2.29–3.00 > ρ >0.72 g/cm3[6] 2.64 g/cm3[7]
Sidereal rotation period	4.13±0.05 h[6][8] 4.14 h[2]
Geometric albedo	0.075+0.076 −0.006 (lower limit)[5] 0.151+0.025 −0.064 (upper limit)[5]
Spectral type	V–R=0.45±0.04[5] BB taxon (blue/neutral)[7][9][c] V−R=0.46±0.06 R−I=0.37±0.06[9]
Apparent magnitude	21[10]
Absolute magnitude (H)	4.38±0.05[5] 4.3 (assumed)[2]

2003 UZ₄₁₃ has been observed 79 times over 15 oppositions, with precovery images back to 27 July 1954.^[2]

Orbit and rotation

Precovery image of 2003 UZ₄₁₃ taken by the Siding Spring Observatory in 1996.^[11]

2003 UZ₄₁₃ is in a 2:3 resonance with Neptune, which means that when it makes two revolutions around the Sun, Neptune makes exactly three.^[3]

The object rotates very fast. In fact, with a period of about 4.13 hours, it is the fastest rotator known in the Kuiper belt after Haumea.^[6][8]

Physical characteristics

The mean diameter of 2003 UZ₄₁₃ is estimated to be 650+1
−175 km, assuming a low albedo.^[5]

Given its rapid rotation, it must have a density higher than 0.72 g/cm³.^[6] Stable Jacobi ellipsoids with an axis ratio of a/b ≥ 1.13±0.03, as implied by its light-curve amplitude of Δm = 0.13±0.03, exist for densities in the range of 2.29−3.00 g/cm³.^[6] Johnston's Archive settles on 2.64 g/cm³,^[7] the centre of the latter range; for a 600 km equivalent spheroid body, this would equate to a mass of approximately 3.0×10²⁰ kg. The extremely high estimated density (in contrast to any known similarly sized TNO)^[12] would make it virtually certain that this object is a dwarf planet, but confirmation would require additional observation to refine the size and light curve details, preferably with discovery of a satellite to determine its mass.

In visible light, this object is neutral or slightly red in color and has a flat, featureless reflectance spectrum.^[8]

Notes

1. Buie page actually says 3:2 resonance... thus, also "Plutino"
2. very approximate figure, assuming equivalent spherical diameter of ≈600 km and density ≈2.64 g/cc³
3. equivalent to V-I=0.75±0.06, B-V=0.68±0.06 and V-R=0.39±0.05