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Ananke (pronounced /əˈnæŋki/ ə-NANG-kee, or as in Greek Ανάγκη) is a retrograde irregular satellite of Jupiter. It was discovered by Seth Barnes Nicholson at Mount Wilson Observatory in 1951[3] and is named after the mythological Ananke, the personification of Necessity, and the mother of the Moirae by Zeus. The adjectival form of the name is Anankean.

Ananke did not receive its present name[4] until 1975;[5] before then, it was simply known as Jupiter XII. It was sometimes called "Adrastea"[6] between 1955 and 1975. Note that Adrastea is now the name of another satellite of Jupiter.

Ananke gives its name to the Ananke group, retrograde irregular moons which orbit Jupiter between 19.3 and 22.7 Gm, at inclinations of roughly 150°.[2]

Retrograde irregular satellites of Jupiter.

Ananke orbits Jupiter on a high eccentricity and high inclination retrograde orbit. Eight irregular satellites discovered since 2000 follow similar orbits.[2] The orbital elements are as of January 2000.[1] They are continuously changing due to Solar and planetary perturbations. The diagram illustrates Ananke's orbit in relation to other retrograde irregular satellites of Jupiter. The eccentricity of selected orbits is represented by the yellow segments (extending from the pericentre to the apocentre). The outermost regular satellite Callisto is located for reference.

Given these orbital elements and the physical characteristics known so far, Ananke is thought to be the largest remnant[7] of an original break-up forming the Ananke group.[8][9]

Physical characteristics

In the visible spectrum, Ananke appears neutral to light-red (colour indices B-V=0.90 V-R=0.38).[9]

The infrared spectrum is similar to P-type asteroids but with a possible indication of water.[10]

See also

* Irregular satellites


1. ^ a b c d e Jacobson, R. A. (2000). "The Orbits of Outer Jovian Satellites". Astronomical Journal 120: 2679–2686. doi:10.1086/316817.
2. ^ a b c d Sheppard, S. S., Jewitt, D. C., Porco, C.; Jupiter's Outer Satellites and Trojans, in Jupiter: The Planet, Satellites and Magnetosphere, edited by Fran Bagenal, Timothy E. Dowling, William B. McKinnon, Cambridge Planetary Science, Vol. 1, Cambridge, UK: Cambridge University Press, ISBN 0-521-81808-7, 2004, pp. 263-280
3. ^ Nicholson, S. B. (1951). "An unidentified object near Jupiter, probably a new satellite". Publications of the Astronomical Society of the Pacific 63 (375): 297–299. doi:10.1086/126402. http://adsabs.harvard.edu//full/seri/PASP./0063//0000297.000.html.
4. ^ Nicholson, S.B. (April 1939). "S. B. Nicholson declines to name the satellites of Jupiter he has discovered". Publications of the Astronomical Society of the Pacific 51 (300): 85–94. doi:10.1086/125010. http://adsabs.harvard.edu//full/seri/PASP./0051//0000093.000.html.
5. ^ Marsden, B. G. (7 October 1974). "Satellites of Jupiter". IAUC Circular 2846. http://cfa-www.harvard.edu/iauc/02800/02846.html.
6. ^ Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-134-78107-4.
7. ^ Sheppard, S.S.; Jewitt, D.C. (2003). "An abundant population of small irregular satellites around Jupiter" ([dead link]). Nature 423 (6937): 261–263. doi:10.1038/nature01584. PMID 12748634. http://www.ifa.hawaii.edu/~jewitt/papers/JSATS/SJ2003.pdf.
8. ^ Nesvorný, D.; Beaugé, C.;Dones, L. (2004). "Collisional Origin of Families of Irregular Satellites". The Astronomical Journal 127: 1768–1783. doi:10.1086/382099. http://www.iop.org/EJ/article/1538-3881/127/3/1768/203442.html.
9. ^ a b Grav, Tommy; Holman, M. J.; Gladman, B. J.; Aksnes, K. (2003). "Photometric survey of the irregular satellites". Icarus 166: 33–45. doi:10.1016/j.icarus.2003.07.005.
10. ^ Grav, Tommy; Holman, Matthew J. (2004). "Near-Infrared Photometry of the Irregular Satellites of Jupiter and Saturn". The Astrophysical Journal 605: L141–L144. doi:10.1086/420881. http://arxiv.org/abs/astro-ph/0312571.

11. Ephemeris IAU-MPC NSES

External links

* Ananke Profile by NASA's Solar System Exploration
* David Jewitt pages
* Scott Sheppard pages

Astronomy Encyclopedia

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