20000 Varuna
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 Artist's idea of what Varuna may look like |
|
| Discovery | |
|---|---|
| Discovered by | R. McMillan (Spacewatch) |
| Discovery time | 28 November 2000 |
| Names | |
| Name | 20000 Varuna |
| Other names | 2000 WR106 |
| Group | TNO (cubewano)[1] |
| Orbit | |
| Reference date 14 July 2004 (JD 2453200.5) | |
| Longest distance from the Sun | 6 781.985 Gm (45.335 AU) |
| Shortest distance from the Sun | 6 120.810 Gm (40.915 AU) |
| Longest distance from the center of its orbital path ("semi-major axis") |
6 451.398 Gm (43.129 AU) |
| How egg-shaped its orbit is ("eccentricity") |
0.051 |
| How long it takes to complete an orbit | 103 440.6 d (283.20 a) |
| Average speed | 4.53 km/s |
| Mean anomaly | 89.673° |
| Angle above the reference plane ("inclination") |
17.2° |
| Longitude of where it comes up through the reference plane | 97.296° |
| Angle between its shortest distance from what it orbits around and where it comes up through the reference plane ("argument of periapsis") |
271.631° |
| Size and Other Qualities | |
| Measures |
800 km (avg of thermals)[2] |
| Mass | ≈3.7×1020? kg[3][5] |
| Average density | 0.992 g/cm³[3] |
| Gravity at its surface | 0.15 m/s² |
| Slowest speed able to escape into space ("escape velocity") |
0.39 km/s |
| How long it takes to turn around one time (in relation to the stars) |
0.132 16 d (3.17 h) |
| How much light it reflects | 0.037–0.26[2] |
| Avg. surface temp. | ≈43–41 K |
| Light-band group ("spectral type") |
(moderately red) B-V=0.93 V-R=0.64[6] |
| Seeming brightness ("apparent magnitude") |
19.9 (opposition)[7] |
| True brightness ("absolute magnitude") |
3.7[8] |
20000 Varuna is a big Kuiper belt object (KBO) and could be a dwarf planet. Before it was named Varuna, it had the provisional designation 2000 WR106.
Varuna is named after the Hindu deity Varuṇa.
Physical characteristics[change | edit source]
Varuna completes one rotation in about 3.17 hours (or 6.34 hours, depending on whether the light curve is single or double-peaked). Given the fast rotation, which is not common for objects so big, Varuna is thought to be a stretched spheroid, with a density around 1g/cm³ (close to the density of water).[4]
The surface of Varuna is somewhat red and small amounts of water ice have been found on its surface.[9]
References[change | edit source]
- ↑ Marc W. Buie (2007-01-12). "Orbit Fit and Astrometric record for 20000". SwRI (Space Science Department). http://www.boulder.swri.edu/~buie/kbo/astrom/20000.html. Retrieved 2008-09-19.
- ↑ 2.0 2.1 Stansberry (2008). "TNO/Centaur diameters and albedos". http://www.johnstonsarchive.net/astro/tnodiam.html. Retrieved 2006-11-08.
- ↑ 3.0 3.1 3.2 Lightcurves Lacerda P., Jewitt D. Dentisities Of Solar System Objects From Their Rotational Lightcurves", accepted to AJ Dec. 2006 Preprint
- ↑ 4.0 4.1 Jewitt D, Sheppard S (2002). "Physical Properties Of Trans-Neptunian Object (20000) Varuna". Astronomical Journal 123 (April): 2110–2120. doi:10.1086/339557. http://www.iop.org/EJ/article/1538-3881/123/4/2110/201498.html. Preprint on arXiv.
- ↑ Calculated using Lacerda and Jewitt (2007) diameter of 900 km and density of 0.992 g/cm³.
- ↑ "TNO and Centaur Colors". http://www.psi.edu/pds/asteroid/EAR_A_COMPIL_3_TNO_CEN_COLOR_V3_0/data/tnocencol.tab. Retrieved 2006-11-08.
- ↑ "HORIZONS Web-Interface". JPL Solar System Dynamics. http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=20000. Retrieved 2008-07-02.
- ↑ "JPL Small-Body Database Browser: 20000 Varuna (2000 WR106)". 2007-11-17 last obs. http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=20000. Retrieved 2008-07-02.
- ↑ Licandro J, Oliva E, Di Martino M (2001). "NICS-TNG infrared spectroscopy of trans-neptunian objects 2000 EB173 and 2000 WR106". Astronomy & Astrophysics 373 (July): 29–32L. doi:10.1051/0004-6361:20010758.
Other websites[change | edit source]
- "Size and Albedo of Kuiper Belt Object (20000) Varuna". David Jewitt's Home Page. http://www.ifa.hawaii.edu/faculty/jewitt/varuna.html. Retrieved 2005-08-15. Site updated Reretrived on 2006-07-10
- Orbital simulation from JPL (Java) / Ephemeris
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