is a bright Kuiper belt object in the outer Solar System estimated to be about in diameter. It is a large member of the Haumea family that was discovered on 15 October 2002 by the Near-Earth Asteroid Tracking (NEAT) program. is a classical Kuiper belt object with an absolute magnitude between that of

50000 Quaoar Quaoar (50000 Quaoar), provisional designation , is a dwarf planet in the Kuiper belt, a region of icy planetesimals beyond Neptune. A non-resonant object (cubewano), it measures approximately in diameter, about half the diameter of Pluto. The ...

and

20000 Varuna 20000 Varuna, provisional designation , is a large trans-Neptunian object in the Kuiper belt. It was discovered in November 2000 by American astronomer Robert McMillan during a Spacewatch survey at the Kitt Peak National Observatory. It is na ...

. has the most eccentric and inclined orbit of the three. A variability of the visual brightness was also detected which could fit to 7.9 h or 15.8 h rotational period (the distinction between single or double-peaked curved could not be made with confidence). The changes in brightness are quite close to the error margin and could also be due to an ''irregular shape''.

Orbit

The adjacent diagrams show polar and ecliptic views of the orbits of the two cubewanos. The

perihelia An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

(q) and the aphelia (Q) are marked with the dates of passage. The present positions (as of April 2006) are marked with the spheres, illustrating relative sizes and differences in albedo (both objects appear neutral in the visible spectrum). is classified as a classical Kuiper belt object and follows an orbit very similar to that of : highly

inclined Incline, inclined, inclining, or inclination may refer to: *Grade (slope), the tilt, steepness, or angle from horizontal of a topographic feature (hillside, meadow, etc.) or constructed element (road, railway, field, etc.) *Slope, the tilt, steepn ...

(26°) and moderately eccentric (e ~0.12), far from

Neptune Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times ...

perturbations Perturbation or perturb may refer to: * Perturbation theory, mathematical methods that give approximate solutions to problems that cannot be solved exactly * Perturbation (geology), changes in the nature of alluvial deposits over time * Perturbatio ...

(perihelion at ~37 AU). Other mid-sized cubewanos follow similar orbits as well, notably and . It has been observed 303 times, with

precovery In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of an object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This happens mos ...

images back to 1954.

Size

In 2004, the non-detection of IR thermal emissions put an upper limit of on its diameter and a lower limit on the albedo of 0.19. In a 2006 International Astronomical Union press release discussing the IAU 2006 draft proposal, a diagram suggested that could be as large as

. The artist's diagram was largely based on the concept that , with an absolute magnitude (H) of 3.4, may have an albedo around 0.08, which resulted in an overly optimistic diameter estimate of around . In 2007, measurements by the

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, f ...

showed that it may be less than in diameter. In 2008, it was considered to be a dwarf planet based on its lightcurve amplitude and the assumption that it was larger than in diameter. Because is a member of the Haumea family, it is assumed to have an albedo of around 0.7, which would result in a diameter of about .

occult The occult, in the broadest sense, is a category of esoteric supernatural beliefs and practices which generally fall outside the scope of religion and science, encompassing phenomena involving otherworldly agency, such as magic and mysticism a ...

ed a relatively bright apparent magnitude 13.1 star in the constellation of Andromeda on 9 October 2009. This event was visible from Australia, possibly New Zealand, and the southern United States and Mexico. The RA and

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the ...

for this event was abou
00 37 13.64 +28 22 23.2.
detailed information for observers was made available. The occultation produced a diameter of , suggesting an albedo of about 0.88. Mike Brown lists it as a possible dwarf planet.

Surface

The spectrum in the visible and near-infrared rages is very similar to that of

Charon In Greek mythology, Charon or Kharon (; grc, Χάρων) is a psychopomp, the ferryman of Hades, the Greek underworld. He carries the souls of those who have been given funeral rites across the rivers Acheron and Styx, which separate the wo ...

, characterized by neutral to blue slope (1%/1000 Å) with deep (60%) water absorption bands at 1.5 and 2.0 μm. Mineralogical analysis indicates a substantial fraction of large ice (H₂O) particles. The signal-to-noise ratio of the observations was insufficient to differentiate between

amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal. Etymology The term comes from the Greek ''a'' ("wi ...

or crystalline ice (crystalline ice was reported on Charon,

Quaoar Quaoar (50000 Quaoar), provisional designation , is a dwarf planet in the Kuiper belt, a region of icy planetesimals beyond Neptune. A non-resonant object (cubewano), it measures approximately in diameter, about half the diameter of Pluto. T ...

and Haumea). The proportion of highly processed organic materials (

tholin Tholins (after the Greek (') "hazy" or "muddy"; from the ancient Greek word meaning "sepia ink") are a wide variety of organic compounds formed by solar ultraviolet or cosmic ray irradiation of simple carbon-containing compounds such as carbon ...

s), typically present on numerous trans-Neptunian objects, is very low. As suggested by Licandro et al. 2006, this lack of irradiated mantle suggest either a recent collision or comet activity.

Origin

Common physical characteristics with the dwarf planet Haumea together with similar orbit elements led to suggestion that was a member of the Haumean collisional family. The object, together with other members of the family (, , and ), would be created from ice mantle ejected from the proto-Haumea as result of a collision with another large (around ) body.

References

External links

AstDys
orbital elements * {{DEFAULTSORT:055636 Haumea family Classical Kuiper belt objects Discoveries by NEAT Objects observed by stellar occultation 20021015