(528219) 2008 KV42

(528219) 2008 KV₄₂ (provisional designation: 2008 KV₄₂; nicknamed Drac)^[3] is a trans-Neptunian object and the first one with a retrograde orbit to be discovered. This retrograde motion with an orbital inclination of 103° suggests that it is the missing link between its source in the Hills cloud and Halley-type comets, thus providing further insight into the evolution of the outer Solar System. The object measures approximately 77 kilometers (48 miles) in diameter. With a semi-major axis of 42 AU, it takes about 269 years to complete an orbit around the Sun.

(528219) 2008 KV₄₂

The orbit of 2008 KV42 is nearly perpendicular to the ecliptic
Discovery[1][2]
Discovered by	CFEPS members: B. Gladman J. J. Kavelaars J.-M. Petit (all unofficial discoverers)
Discovery site	Mauna Kea Obs.
Discovery date	31 May 2008
Designations
MPC designation	(528219) 2008 KV42
Alternative designations	2008 KV42 · Drac[3]
Minor planet category	TNO[4] · centaur[5][6] damocloid[7] · distant[1]
Orbital characteristics[4]
Epoch 1 July 2021 (JD 2459396.5)
Uncertainty parameter 3[4] · 1[1]
Observation arc	12.20 yr (4,456 d)
Aphelion	62.917 AU
Perihelion	21.152 AU
Semi-major axis	42.035 AU
Eccentricity	0.4968
Orbital period (sidereal)	272.53 yr (99,543 d)
Mean anomaly	341.23°
Mean motion	0° 0m 12.96s / day
Inclination	103.41°
Longitude of ascending node	260.91°
Argument of perihelion	132.61°
Uranus MOID	4.26 AU[1]
TJupiter	-1.0210
Physical characteristics
Mean diameter	77 km (est. at 0.09)[6]
Apparent magnitude	22.89[8]
Absolute magnitude (H)	8.8[1][4]

Officially discovered on 31 May 2008, the discovery was announced on 16 July 2008, by the Canada–France Ecliptic Plane Survey team led by Brett Gladman. The discovery team nicknamed 2008 KV₄₂ "Drac" after Count Dracula.

Discovery and naming

The discovery of 2008 KV₄₂ was announced on 16 July 2008 by the Canada–France Ecliptic Plane Survey team led by Brett Gladman from the University of British Columbia.^[9] The announcement was made during the "Asteroids, Comets, Meteors" meeting held in Baltimore, Maryland, followed by a Minor Planet Electronic Circular on the same day and an IAU Circular on 18 July. The discovery was made using images obtained on 31 May from the 3.5-meter Canada-France-Hawaii Telescope, followed by further observations until 8 July from the Whipple Observatory and Cerro Tololo.^[2][10]

The discovery team nicknamed 2008 KV₄₂ "Drac" because of its high inclination in reference to its orbital plane resembling Count Dracula's ability to walk on walls.^[11]

Orbit

Polar view and side view of the orbits of 2008 KV₄₂ (pink) and 471325 Taowu (white)

2008 KV₄₂ is the first trans-Neptunian object (TNO) with a retrograde orbit to be discovered. With a semi-major axis of 41.7 AU,^[4] it was discovered while at a distance of 32 AU and has a perihelion at roughly the distance of Uranus.

The object's 103° inclination makes its almost perpendicular to the ecliptic, and is, as of July 2017, one of only six objects known to have inclination and perihelion larger than 60° and 15 AU, respectively. The other five are: 2002 XU93, 2007 BP102, 2010 WG9, 471325 Taowu, and 2014 LM28.^[12][13]

Its unusual orbit suggests that 2008 KV₄₂ may have been perturbed inwards from its source, most likely in the Hills cloud, by an unknown gravitational disturbance. Its discovery may reveal the source regions for Halley-type comets which also have an retrograde orbit, but their origin remains unknown. 2008 KV₄₂ itself is believed to be in an intermediate stage towards becoming a comet, thus helping to further explain the formation and evolution of the outer Solar System.^[14][15][3]

Planet Nine

2008 KV₄₂ may even provide evidence of Planet Nine.^[16] The Kozai effect inside the mean-motion resonances with Planet Nine may cause a periodic exchange between its inclination and its eccentricity. When the elongated perpendicular centaurs get too close to a giant planet, orbits such as that of 2008 KV₄₂ are created.^[17]

See also

• List of trans-Neptunian objects
• 471325 Taowu