Cybele asteroid

The Cybele asteroids (also known as the "Cybeles") are a dynamical group of asteroids, named after the asteroid 65 Cybele.[1] Considered by some as the last outpost of an extended asteroid belt, the group consists of just over 2000 members and a few collisional families.[2][3] The Cybeles are in a 7:4 orbital resonance with Jupiter. Their orbit is defined by an osculating semi-major axis of 3.28 to 3.70 AU,[2] with an eccentricity of less than 0.3, and an inclination less than 25°.[1]

The dynamical Cybele group is located adjacent to the outermost asteroid belt, beyond the Hecuba gap – the 2:1 resonant zone with Jupiter, where the Griqua asteroids are located – and inside the orbital region of the Hilda asteroids (3:2 resonance), which are themselves followed by the Jupiter trojans (1:1 resonance) further out.


Three known asteroid families exist within the Cybele group: the Sylvia family (603), the Huberta family and the Ulla family (903). A potential fourth family is a small cluster with the parent body (45657) 2000 EK.[2] A fifth family, named after 522 Helga, was identified in 2015.[3]

The Cybele asteroids 87 Sylvia and 107 Camilla are triple systems with more than one satellite. Other large members include 121 Hermione, 76 Freia, 790 Pretoria, and 566 Stereoskopia.[1]

The group is thought to have formed from the breakup of a larger object in the distant past.[1] While most members are C- and X-type asteroids, NASA's Wide-field Infrared Survey Explorer also measured albedos of some Cybele asteroids that are typical for stony S-type asteroids.[2]


Total of 2034 Cybeles with osculating semi-major axis between 3.28 and 3.7 AU. Low numbered members of the collisional Sylvia (SYL) and smaller Ulla (ULA) families are also marked.

See also[]


  1. ^ a b c d Elkins-Tanton, Linda T. (2010). Asteroids, Meteorites, and Comets. p. 96. ISBN 9781438131863. Retrieved 27 April 2018.
  2. ^ a b c d Carruba, V.; Domingos, R. C.; Nesvorný, D.; Roig, F.; Huaman, M. E.; Souami, D. (August 2013). "A multidomain approach to asteroid families' identification". Monthly Notices of the Royal Astronomical Society. 433 (3): 2075–2096. arXiv:1305.4847. Bibcode:2013MNRAS.433.2075C. doi:10.1093/mnras/stt884. S2CID 118511004.
  3. ^ a b Carruba, V.; Nesvorný, D.; Aljbaae, S.; Huaman, M. E. (July 2015). "Dynamical evolution of the Cybele asteroids". Monthly Notices of the Royal Astronomical Society. 451 (1): 244–256. arXiv:1505.03745. Bibcode:2015MNRAS.451..244C. doi:10.1093/mnras/stv997. S2CID 119246717.