Caliban (moon)
Discovery image of Caliban
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Discovery[1]
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| Discovered by | using the Hale telescope |
| Discovery date | September 6, 1997 |
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Designations
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| Adjective | Calibanian |
| Mean orbit radius | 7,231,000 km[2][3] |
| Eccentricity | 0.1812[3] |
| Orbital period | 579.73 d |
| Inclination |
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| Satellite of | Uranus |
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Physical characteristics
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| Mean radius | 36 km (estimate)[4][5] |
| Surface area | ~16,000 km² (estimate) |
| Volume | ~200,000 km³ (estimate) |
| Mass | ~2.5×1017 kg (estimate) |
| Mean density | ~1.3 g/cm³ (assumed) |
| Rotation period | 2.7h[6] |
| Axial tilt | ? |
| Albedo | 0.04 (assumed)[4] |
| Temperature | ~65 K (estimate) |
Caliban (
/ˈkælɨbæn/ kal-i-ban or /ˈkælɨbən/ kal-ə-bən) is the second largest retrograde irregular moon of Uranus.[4] It was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J. Kavelaars using the 200-inch Hale telescope together with Sycorax and given the temporary designation S/1997 U 1.[1]
Designated Uranus XVI, it was named after the monster character in William Shakespeare's play The Tempest.
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[edit] Orbit
Caliban follows a distant orbit, more than 10 times further from Uranus than the furthest regular moon Oberon.[1] Its orbit is retrograde, moderately inclined and slightly eccentric. The orbital parameters suggest that it may belong to the same dynamic cluster as Stephano and Francisco, suggesting common origin.[7]
The diagram illustrates the orbital parameters of the retrograde irregular satellites of Uranus (in polar co-ordinates) with the eccentricity of the orbits represented by the segments extending from the pericentre to the apocentre.
[edit] Physical characteristics
Its diameter is estimated at 72 km (assuming albedo of 0.04)[4][5] making it the second largest irregular satellite of Uranus, half the size of Sycorax, the biggest irregular satellite of Uranus.
Somewhat inconsistent reports put Caliban in light-red category (B–V = 0.83 V–R = 0.52,[8] B–V = 0.84 ± 0.03 V–R = 0.57 ± 0.03[7]), redder than Himalia but still less red than most Kuiper belt objects. Caliban may be slightly redder than Sycorax.[6] It also absorbs light at 0.7 μm, and one group of astronomers think this may be a result of liquid water that modified the surface.[9]
The light curve suggests the rotation period of Caliban is about 2.7h.[6]
[edit] Origin
Caliban is hypothesized to be a captured object: it did not form in the accretionary disk that existed around Uranus just after its formation. The exact capture mechanism is not known, but capturing a moon requires the dissipation of energy. The possible capture processes include: gas drag in the protoplanetary disk, many body interactions and the capture during the fast growth of the Uranus' mass (so-called "pull-down").[4][7]
[edit] See also
[edit] References
- ^ a b c Gladman, Brett J.; Nicholson, Philip D.; Burns, Joseph A.; Kavelaars, JJ; Marsden, Brian G.; Williams, Gareth V.; Offutt, Warren B. (1998). "Discovery of two distant irregular moons of Uranus". Nature 392 (6679): 897–899. Bibcode 1998Natur.392..897G. doi:10.1038/31890.
- ^ Sheppard 2005, p. 523
- ^ a b Brozovic, M.; Jacobson, R. A. (2009). "Planetary Satellite Mean Orbital Parameters". The Orbits of the Outer Uranian Satellites, Astronomical Journal, 137, 3834. JPL/NASA. http://ssd.jpl.nasa.gov/?sat_elem#uranus. Retrieved 2011-11-06.
- ^ a b c d e f Sheppard, Scott S.; Jewitt, David C.; Kleyna, Jan (2005). "An Ultradeep Survey for Irregular Satellites of Uranus: Limits to Completeness" (PDF). The Astronomical Journal 129 (1): 518–525. arXiv:astro-ph/0410059. Bibcode 2005AJ....129..518S. doi:10.1086/426329. http://www.ifa.hawaii.edu/~jewitt/papers/2005/SJK2005.pdf. Retrieved 20 October 2009. "Table 3 ... ri (km) ... 36 ... i Radius of satellite assuming a geometric albedo of 0.04."[dead link]
- ^ a b "Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). 20 December 2008. http://ssd.jpl.nasa.gov/?sat_phys_par. Retrieved 10 March 2009.
- ^ a b c Maris, Michele; Giovanni Carraro, Gabrielle Cremonese, Marco Fulle (May 2001). "Multicolor Photometry of the Uranus Irregular Satellites Sycorax and Caliban". The Astronomical Journal 121 (5): 2800–2803. arXiv:astro-ph/0101493. Bibcode 2001AJ....121.2800M. doi:10.1086/320378. http://www.iop.org/EJ/article/1538-3881/121/5/2800/200443.html. Retrieved 14 September 2008.
- ^ a b c Grav, Tommy; Holman, Matthew J.; Fraser, Wesley C. (2004-09-20). "Photometry of Irregular Satellites of Uranus and Neptune". The Astrophysical Journal 613 (1): L77–L80. arXiv:astro-ph/0405605. Bibcode 2004ApJ...613L..77G. doi:10.1086/424997.
- ^ Rettig, Terrence W.; Walsh, Kevin; Consolmagno, Guy (December 2001). "Implied Evolutionary Differences of the Jovian Irregular Satellites from a BVR Color Survey". Icarus 154 (2): 313–320. Bibcode 2001Icar..154..313R. doi:10.1006/icar.2001.6715.
- ^ Schmude, Richard (2008). Uranus, Neptune, Pluto and How to Observe Them. Springer. ISBN 0387766014, 9780387766010. http://books.google.com/?id=kqNr7rjw028C&pg=PA58&lpg=PA58#v=onepage&q=.
[edit] External links
- Caliban Profile by NASA's Solar System Exploration
- David Jewiit pages
- Uranus' Known Satellites (by Scott S. Sheppard)
- MPC: Natural Satellites Ephemeris Service
- Caliban and Sycorax, Moons of Uranus (2005 Calvin J. Hamilton)
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