(612093) 1999 LE31

(612093) 1999 LE₃₁, prov. designation: 1999 LE₃₁, is a centaur and damocloid on a retrograde and eccentric orbit from the outer region of the Solar System. It was first observed on 12 June 1999, by astronomers with the LINEAR program at the Lincoln Lab's ETS near Socorro, New Mexico, in the United States.^[1] The unusual object measures approximately 17 kilometers (11 miles) in diameter.^[2][3]

(612093) 1999 LE₃₁

Orbital diagram of the orbit of 1999 LE31
Discovery[1]
Discovered by	LINEAR
Discovery site	Lincoln Lab ETS
Discovery date	12 June 1999
Designations
MPC designation	(612093) 1999 LE31
Alternative designations	1999 LE31
Minor planet category	centaur[2] · damocloid[3] unusual[4] · distant[1]
Orbital characteristics[2]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 2
Observation arc	19.23 yr (7,022 d)
Aphelion	11.913 AU
Perihelion	4.3396 AU
Semi-major axis	8.1265 AU
Eccentricity	0.4660
Orbital period (sidereal)	23.17 yr (8,462 d)
Mean anomaly	316.77°
Mean motion	0° 2m 33s / day
Inclination	151.81°
Longitude of ascending node	292.12°
Argument of perihelion	32.319°
Jupiter MOID	0.517 AU
TJupiter	-1.3090
Physical characteristics
Mean diameter	16.8±4.2 km[2][3]
Geometric albedo	0.056±0.026[2][3]
Spectral type	B–R = 1.20[3]
Absolute magnitude (H)	12.5[1][2]

Description

1999 LE₃₁ orbits the Sun at a distance of 4.3–11.9 AU once every 23 years and 2 months (8,462 days; semi-major axis of 8.13 AU). Its orbit has an eccentricity of 0.47 and an inclination of 152° with respect to the ecliptic.^[2]

It spends most of its orbit located in the outer Solar System between Jupiter and Uranus,^[5] and like all centaurs, has an unstable orbit caused by the gravitational influence of the giant planets. Due to this, it must have originated from elsewhere, most likely outside Neptune.^[5] It is both a Jupiter and Saturn-crossing minor planet.^[2] Of over half a million known minor planets, 1999 LE₃₁ is one of about 60 that has a retrograde orbit.^[6]

1999 LE₃₁ is approximately 16.8 km in diameter.^[2][3] It came to perihelion (closest approach to the Sun) in December 1998.^[7] It was last observed in 2000, and will next come to perihelion in February 2022.^[2]

Observations

This asteroid has been recorded at such observatories as:^[1]

• Lincoln Laboratory (1.0-m f/2.15 reflector + CCD) - location of discovery
• Dominion Astrophysical Observatory (1.82-m reflector + CCD)
• Dynic Astronomical Observatory (0.60-m f/3.7 reflector + CCD)
• European Northern Observatory (1.0-m reflector + CCD)
• Farpoint (0.30-m Schmidt-Cassegrain + CCD)
• Kleť Observatory (0.57-m f/5.2 reflector + CCD)
• McDonald Observatory (0.76-m reflector + CCD)
• Roque de los Muchachos Observatory (1.0-m reflector + CCD)

See also

• 20461 Dioretsa a.k.a. 1999 LD₃₁
• 2000 DG8
• List of exceptional asteroids