Ananke (moon)

This article is about Jupiter's irregular moon. For the mythological figure, see Ananke (mythology).
Ananke
Discovery
Discovered by S. B. Nicholson
Discovery date September 28, 1951
Orbital characteristics
Periapsis 12,567,000 km
Apoapsis 29,063,500 km
Mean orbit radius
 21,280,000 km[1]
Eccentricity 0.24[1]
610.45 d (1.680 a)[1]
2.367 km/s
Inclination 148.89° (to the ecliptic)
149.9° (to Jupiter's equator)[1]
Satellite of Jupiter
Physical characteristics
Mean radius
 14 km[2]
~2500 km2
Volume ~11,500 km3
Mass 3.0×1016 kg
Mean density
 2.6 g/cm3 (assumed)
0.010 m/s2 (0.001 g)
~0.017 km/s
Albedo 0.04 (assumed)[2]
Temperature ~124 K

    Ananke (/əˈnæŋkiː/ ə-NANG-kee; Greek: Ανάγκη) is a retrograde irregular moon 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 Moirai 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 (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]

    Orbit

    Ananke orbits Jupiter on a high eccentricity and high inclination retrograde orbit. Eight irregular satellites have been discovered since 2000 following 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]

    Retrograde irregular satellites of Jupiter.

    See also

    References

    1. 1 2 3 4 5 Jacobson, R. A. (2000). "The Orbits of Outer Jovian Satellites". Astronomical Journal 120 (5): 2679–2686. Bibcode:2000AJ....120.2679J. doi:10.1086/316817.
    2. 1 2 3 4 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. Bibcode:1951PASP...63..297N. doi:10.1086/126402.
    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. Bibcode:1939PASP...51...85N. doi:10.1086/125010.
    5. ↑ Marsden, B. G. (7 October 1974). "Satellites of Jupiter". IAUC Circular 2846.
    6. ↑ Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-13-478107-4.
    7. ↑ Sheppard, S.S.; Jewitt, D.C. (2003). "An abundant population of small irregular satellites around Jupiter" (PDF). Nature 423 (6937): 261–263. Bibcode:2003Natur.423..261S. doi:10.1038/nature01584. PMID 12748634. Archived from the original (PDF) on August 13, 2006.
    8. ↑ Nesvorný, D.; Beaugé, C.; Dones, L. (2004). "Collisional Origin of Families of Irregular Satellites". The Astronomical Journal 127 (3): 1768–1783. Bibcode:2004AJ....127.1768N. doi:10.1086/382099.
    9. 1 2 Grav, Tommy; Holman, M. J.; Gladman, B. J.; Aksnes, K. (2003). "Photometric survey of the irregular satellites". Icarus 166 (1): 33–45. arXiv:astro-ph/0301016. Bibcode:2003Icar..166...33G. 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 (2): L141–L144. arXiv:astro-ph/0312571. Bibcode:2004ApJ...605L.141G. doi:10.1086/420881.

    Sources

    External links

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