is an unnamed trans-Neptunian object (TNO) in the Kuiper belt. It is a member of the plutinos, a population of TNOs in a 2:3 orbital resonance with Neptune, like Pluto. It was discovered by the Near-Earth Asteroid Tracking program at Palomar Observatory on 14 November 2003. It is an elongated object with a diameter measuring across its longest axis to across its shortest.

Discovery was discovered by the NASA-funded Near-Earth Asteroid Tracking (NEAT) project on 14 November 2003, during routine observations of the sky at Palomar Observatory in California, United States. The discovery observations were made using the observatory's Samuel Oschin telescope, which was equipped with a charge-coupled device camera. Astronomers of the project flagged as an "interesting object" because it moved much slower than near-Earth objects that NEAT was tasked to find. The object was listed on the Minor Planet Center's (MPC's) Near-Earth Object Confirmation Page, which prompted follow-up observations from other observatories.

Within two days after the discovery of , astronomers began finding precoveries of the object in older NEAT images. Precoveries were first found by Maik Meyer in images from late 2002, and then by Sebastian Hönig in images from 1998, 2001, and 2002. These extra observations allowed astronomers to determine the orbit of . The discovery and confirmation of was announced by the MPC on 16 November 2003. Subsequent reports of the discovery, including those from the NEAT project, recognized as one of the largest trans-Neptunian objects found.

On the day after the MPC's announcement of , astronomer Reiner Stoss reported more precoveries from Palomar Observatory's Digitized Sky Survey, whose images were taken even earlier in 1991 and 1993. The earliest of these precoveries was taken on 17 September 1991. These precoveries were independently found by Andrew Lowe and Rob Matson around the same time as Stoss.

Name This object is currently known by its minor planet provisional designation , which was given by the MPC upon its discovery. The provisional designation encodes the object's time and order of discovery. The MPC gave it the minor planet number (84922) on 4 May 2004. When it was discovered, the object was initially codenamed "3A86VCM" by the NEAT project. , it has not been named. According to naming guidelines by the International Astronomical Union's Working Group for Small Bodies Nomenclature, trans-Neptunian objects classified as plutinos should be given mythological names related to the underworld.

Orbit orbits the Sun with a semi-major axis of 39.4 astronomical units (AU), putting it in the Kuiper belt beyond Neptune's orbit. takes 247 years to complete one orbit, which places it in a 2:3 mean-motion resonance with Neptune. For every two revolutions it makes around the Sun, Neptune makes exactly three. It is therefore a member of the plutinos, a large population of trans-Neptunian objects (TNOs) named after its largest member Pluto.

has a nearly circular orbit with a low eccentricity of 0.08. Its orbit is inclined by 14.8° with respect to the ecliptic. Throughout its orbit, the object's distance from the Sun ranges from at perihelion to at aphelion. had passed perihelion on 8 March 2005. Due to gravitational perturbations by the giant planets, the orbital elements of vary over time. Simulations of 's orbit show that in 10 million years, its semi-major axis can fluctuate between , eccentricity between 0.05–0.11, and inclination between 15.4–16.8°. Despite this variability, the orbit of remains stable for billions of years.

Physical characteristics Size and shape In 2007, its diameter was initially estimated by the Spitzer Space Telescope at . However, in 2012, this was reduced to after new Herschel Space Telescope observations. In 2019, was found to be ellipsoidal in shape based on stellar occultations that occurred in 2013 and 2014; the light curve derived from the occultations suggests that this plutino is not in hydrostatic equilibrium and hence not a dwarf planet. The dimensions of are estimated at , with a volume-equivalent diameter of .

Further observations of occultations refined the estimate to  ×  ×  km, with a mean diameter of .

has no known satellite that can be used to directly determine its mass, but assuming a density of 1 g/cm3, typical of mid size TNOs, gives a mass estimate of about 6.5 kg. it has an estimated density of , if assuming that it is a Maclaurin Spheroid.

Surface

has a moderately red surface with a moderately red color indices B−V=0.93, V−R=0.59. Its geometrical albedo is about 0.13.

Rotation

rotates with a period of approximately 7.42 hours, measured to an accuracy of 0.04 seconds. It has a high light curve amplitude of , indicative of an elongated, non-spherical shape.

See also 90377 Sedna – a dwarf planet discovered on the same day as (14 November 2003) 208996 Achlys – a large plutino and possible dwarf planet with an elongated ellipsoid shape – a similarly-sized trans-Neptunian object whose shape has been characterized by stellar occultations – another similarly-sized trans-Neptunian object whose shape has been characterized by stellar occultations – a similarly-sized plutino discovered to have an atmosphere in stellar occultation observations

Notes

References

External links

Huge rock-ice body circles Sun (Palomar Photo) 2003 VS2 precovery (18 Nov. '03 Major News about Minor Objects)