20000 Varuna
Encyclopedia : 2 : 20 : 200 : 20000 Varuna
| Orbital elements | |
|---|---|
| Eccentricity (orbit)>e | |
| Inclination>i | ° |
| Perihelion>q | AU |
| Argument of perihelion>ω | ° |
| Semi-major axis>a | AU |
| Longitude of the ascending node>ω | ° |
| Aphelion>Q | AU |
| Mean anomaly>M | ° |
| Orbital period>P | years |
| Mean motion>n | °/day |
| Time of perihelion passage>TP | |
It is named after the Hindu god Varuna. It previously had the provisional designation 2000 WR106 and has been precovered in plates dating back to 1953.
Orbit
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Varuna is classified as a classical trans-Neptunian object and follows a near-circular orbit with a semi-major axis of ~43 AU, similar to that of 50000 Quaoar but more inclined. The graph shows the polar view (top; Varuna’s orbit in blue, Pluto’s in red, Neptune in grey). The spheres illustrate the current (April 2006) positions, relative sizes and colours. The perihelia (q), aphelia (Q) and the dates of passage are also marked. Interestingly, the orbits of Varuna and Pluto have similar inclination and are similarly oriented (the nodes of both orbits are quite close).
At 43 AU and on a near-circular orbit, unlike Pluto which is in 2:3 orbital resonance with Neptune, Varuna is free from any significant perturbation from Neptune. The ecliptic view illustrates the comparison of Varuna's near-circular orbit with that of Pluto (highly eccentric, e=0.25), both similarly inclined.
Physical characteristics
Varuna has a rotational period of approximately 3.17 hours (or 6.34 hours, depending on whether the light curve is single or double-peaked). Given the rapid rotation, unknown at this time (2002) for objects so large, (Jewitt & Sheppard, 2002) consider possible models for the shape and density concluding that the most probable interpretation fitting the data is an elongated spheroid (ratio of axis 2:3), composed from a porous mixture of rock, with a mean density around 1g/cm3 (roughly the density of water ice). Since then, another even larger, rapidly rotating (3.9 h) object 2003 EL61 has been discovered. An elongated shape was also suggested in that case (see references there).The surface is moderately red (similar to 50000 Quaoar) but exceptionally dark (albedo<0.04) compared with other large classical Kuiper Belt objects indicating it is largely devoid of ice. (Jewitt, et al., 2001)
References
- [Preprint on arXiv.]
- [Preprint on arXiv.]
- PMID 11373669. [Reprint] on the Author's site.
External links
- Site updated Reretrived on 2006-07-10
- [Orbit simulation from NASA JPL site]
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| Large trans-Neptunian objects[http://encycl.opentopia.com/ edit ] |
| Kuiper belt: Pluto (Charon) | Orcus | Ixion | 2002 UX25 | Varuna | 2002 TX300 | 2003 EL61 | Quaoar | 2005 FY9 | 2002 AW197 |
| Scattered disc: 2002 TC302 | 2003 UB313 | 2004 XR190 | Sedna† |
| See also Triton, astronomical objects and the solar system's list of objects, sorted by radius or mass. For pronunciation, see: Centaur and TNO pronunciation. † Current MPC classification. Some consider Sedna an Oort cloud object. |
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| For other objects and regions, see: , , asteroid moons and the Solar system For a complete listing, see: List of asteroids. See also Pronunciation of asteroid names and Meanings of asteroid names. |
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