Ananke group

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The Ananke group is a group of retrograde non-spherical moons of Jupiter that follow similar orbits to Ananke and are thought to have a common origin.

Their semi-major axes (distances from Jupiter) range between 19,300,000 and 22,700,000 km, their inclinations between 145.7° and 154.8°, and their orbital eccentricities between 0.02 and 0.28.

This diagram illustrates the largest irregular satellites of Jupiter. The location of the Ananke group is illustrated by Ananke's presence near the bottom. An object's position on the horizontal axis indicates its distance from Jupiter. The vertical axis indicates its inclination. Eccentricity is indicated by yellow bars illustrating the object's maximum and minimum distances from Jupiter. Circles illustrate an object's size in comparison to the others.

The core members include (from biggest to smallest):[1][2]

The International Astronomical Union (IAU) reserves names ending in -e for all retrograde moons, including this group's members.

Origin[change | change source]

The Ananke group is believed to have been formed when an asteroid was captured by Jupiter and broken apart by a collision.

Based on the sizes of the moons, the original asteroid may have been about 28 km in diameter. Since this value is near the approximate diameter of Ananke itself, it is likely the parent body was not heavily disrupted.[3]

Three of the moons of the family (Harpalyke, Praxidike and Iocaste) display similar grey colours while Ananke itself is on the boundary between grey and light red.[4]

This diagram compares the orbital elements and relative sizes of the core members of the Carme group. The horizontal axis illustrates their average distance from Jupiter, the vertical axis their orbital inclination, and the circles their relative sizes.
This diagram offers a wider field of view than the previous one, showing other small moons clustered near the core Ananke group.


References[change | change source]

  1. Scott S. Sheppard, David C. Jewitt, Carolyn Porco 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, p. 263 - 280 Full text(pdf).
  2. David Nesvorný, Cristian Beaugé, and Luke Dones Collisional Origin of Families of Irregular Satellites, The Astronomical Journal, 127 (2004), pp. 1768–1783 Full text.
  3. Sheppard, Scott S.; Jewitt, David C. (May 5 2003). "An abundant population of small irregular satellites around Jupiter". Nature 423: 261–263. doi:10.1038/nature01584 . (pdf).
  4. Grav, Tommy; Holman, Matthew J.; Gladman, Brett J.; Aksnes, Kaare Photometric survey of the irregular satellites,Icarus, 166,(2003), pp. 33-45. Preprint