Ananke (moon)

Ananke /əˈnæŋkiː/ is a retrograde irregular moon of Jupiter. It was discovered by Seth Barnes Nicholson at Mount Wilson Observatory in 1951[7] and is named after the mythological Ananke, the personification of Necessity, and the mother of the Moirai (Fates) by Zeus. The adjectival form of the name is Anankean.

Ananke
Discovery
Discovered byS. B. Nicholson
Discovery dateSeptember 28, 1951
Designations
Designation
Jupiter XII
Pronunciation/əˈnæŋkiː/[1]
Named after
Ἀνάγκη Anagkē
AdjectivesAnankean /ænəŋˈkiːən/[2]
Orbital characteristics [3]
21276000 km
Eccentricity0.244
−610.5 days
248.8°
Inclination148.9°
7.6°
100.6°
Satellite ofJupiter
GroupAnanke group
Physical characteristics
Mean diameter
29.1±0.6 km[4]
Mean density
2.6 g/cm3 (assumed)[5]
8.3±0.1 h[6]
Albedo0.038±0.006[4]
Temperature~124 K
18.9

    Ananke did not receive its present name[8] until 1975;[9] before then, it was simply known as Jupiter XII. It was sometimes called "Adrastea"[10] 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°.[11]

    Orbit
    Retrograde irregular satellites of Jupiter.

    Ananke orbits Jupiter on a high-eccentricity and high-inclination retrograde orbit. Eight irregular satellites orbiting Jupiter have been discovered since 2000 following similar orbits.[11] The orbital elements are as of January 2000.[12] 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[13] of an original break-up forming the Ananke group.[14][15]

    Physical characteristics
    Single-exposure image of Ananke by the Wide-field Infrared Survey Explorer (WISE) spacecraft in 2010

    In the visible spectrum, Ananke appears neutral to light-red (colour indices B-V=0.90 V-R=0.38).[15]

    The infrared spectrum is similar to P-type asteroids but with a possible indication of water.[16]

    See also
    • Irregular satellites

    References
    1. "Ananke". Dictionary.com Unabridged. Random House.
    2. Yenne (1987) The Atlas of the Solar System.
    3. S.S. Sheppard (2019), Moons of Jupiter, Carnegie Science, on line
    4. Grav, T.; Bauer, J. M.; Mainzer, A. K.; Masiero, J. R.; Nugent, C. R.; Cutri, R. M.; et al. (August 2015). "NEOWISE: Observations of the Irregular Satellites of Jupiter and Saturn". The Astrophysical Journal. 809 (1): 9. Bibcode:2015ApJ...809....3G. doi:10.1088/0004-637X/809/1/3. 3.
    5. "Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). 2008-10-24. Retrieved 2008-12-12.
    6. Luu, Jane (September 1991). "CCD photometry and spectroscopy of the outer Jovian satellites". Astronomical Journal. 102: 1213–1225. Bibcode:1991AJ....102.1213L. doi:10.1086/115949. ISSN 0004-6256.
    7. 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.
    8. 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.
    9. Marsden, B. G. (7 October 1974). "Satellites of Jupiter". IAU Circular. 2846.
    10. Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-13-478107-4.
    11. Sheppard, S. S., Jewitt, D. C., Porco, C.; Jupiter's Outer Satellites and Trojans Archived 2007-06-14 at the Wayback Machine, 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
    12. Jacobson, R. A. (2000). "The Orbits of Outer Jovian Satellites" (PDF). Astronomical Journal. 120 (5): 2679–2686. Bibcode:2000AJ....120.2679J. doi:10.1086/316817.
    13. 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.
    14. 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.
    15. 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.
    16. 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

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