65 Cybele

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65 Cybele
65 Cybele.png
Lightcurve-based 3D-model of Cybele
Discovery [1][2]
Discovered by E. W. Tempel
Discovery site Marseille Obs.
Discovery date 8 March 1861
MPC designation (65) Cybele
Pronunciation /ˈsɪbəli/ SIB-ə-lee
Named after
(Hellenistic deity)
1949 YQ
main belt · (outer)[1]
Orbital characteristics
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 155.98 yr (56,971 d)
Aphelion 3.8102 AU
Perihelion 3.0464 AU
3.4283 AU
Eccentricity 0.1114
6.35 yr (2,319 days)
0° 9m 19.08s / day
Inclination 3.5627°
Physical characteristics
Dimensions (302×290×232) km[5]
218.56±50.88 km[6]
237.26±4.2 km[7]
273.0±11.9 km[5]
276.58±74.49 km[8]
300.54 km[9]
Mass 1.78×1019 kg[10]
Mean density
0.99±0.20 g/cm³[10]
6.0814 h[11]
Tholen = P [1]
SMASS = Xc [1] · X[11]
10.67 to 13.64
6.58±0.06[12] · 6.62[1][7][8][9][11] · 6.88±0.26[13] · 6.95[6]

65 Cybele (/ˈsɪbəli/ SIB-ə-lee) is one of the largest asteroids in the Solar System and is located in the outer asteroid belt. It gives its name to the Cybele family of asteroids[4] that orbit outward from the Sun from the 2:1 orbital resonance with Jupiter. It is a X-type asteroid, meaning that it is dark in color and carbonaceous[clarification needed] in composition. It was discovered by Wilhelm Tempel in 1861, and named after Cybele, the earth goddess.

Discovery and naming[edit]

Cybele was discovered on 8 March 1861, by German astronomer Ernst Tempel from the Marseilles Observatory in France. A minor controversy arose from its naming process.[2] Tempel had awarded the honour of naming the asteroid to Carl August von Steinheil in recognition of his achievements in telescope production. Von Steinheil elected to name it "Maximiliana" after the reigning monarch Maximilian II of Bavaria, at the time, asteroids were conventionally given classical names, and a number of astronomers protested this contemporary appellation. The name Cybele was chosen instead, referring to the Phrygian goddess of the earth.[3] (The previously discovered 45 Eugenia, 54 Alexandra, and 64 Angelina had nevertheless also been given non-classical names; 64 Angelina had also been discovered by Tempel, but its name stood despite similar protests.)

Physical characteristics[edit]

The first Cybelian stellar occultation was observed on 17 October 1979, in the Soviet Union, the asteroid appeared to have an irregular shape, with the longest chord being measured as 245 km, closely matching results determined by the IRAS satellite in 1983 (see below). During the same 1979 occultation, a hint of a possible 11 km wide minor-planet moon at 917 km distance was detected,[14] but has since never been corroborated. As of 2017, neither the Asteroid Lightcurve Data Base nor Johnston's archive consider Cybele to be a binary asteroid.[11][15]

Diameter estimates[edit]

Mean-diameter estimates for Cybele range between 218.56 and 300.54 kilometers. According to observations by the Infrared Astronomical Satellite IRAS in 1983, the asteroid has a diameter of 237.26 km.[7] The NEOWISE mission of NASA's Wide-field Infrared Survey Explorer gave a diameter of 218.56 and 276.58 km.[6][8] The largest estimates of 300.54 km is from the Japanese Akari satellite.[9] In 2004, Müller estimated Cybele using thermophysical modelling (TPM) to have dimensions of 302×290×232 km, which corresponds to a mean-diameter of 273.0 km.[5]


Examination of the asteroid's infrared spectrum shows an absorption feature that is similar to the one present in the spectrum of 24 Themis, this can be explained by the presence of water ice. The asteroid may be covered in a layer of fine silicate dust mixed with small amounts of water-ice and organic solids.[16]

Recent occultations[edit]

On August 24, 2008, Cybele occulted 2UCAC 24389317, a 12.7-magnitude star in the constellation Ophiuchus which showed a long axis of at least 294 km.[17] On 11 October 2009, Cybele occulted a 13.4-magnitude star in the constellation Aquarius.[18]


  1. ^ a b c d e "JPL Small-Body Database Browser: 65 Cybele". 2010-11-23 last obs. Retrieved 2008-11-25. 
  2. ^ a b "(65) Cybele". Minor Planet Center. Retrieved 21 April 2017. 
  3. ^ a b Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (65) Cybele. Springer Berlin Heidelberg. p. 21. ISBN 978-3-540-00238-3. Retrieved 21 April 2017. 
  4. ^ a b Linda T. Elkins-Tanton - Asteroids, Meteorites, and Comets (2010) - Page 96 (Google Books)
  5. ^ a b c d Müller, T. G.; Blommaert, J. A. D. L. (April 2004). "65 Cybele in the thermal infrared: Multiple observations and thermophysical analysis". Astronomy and Astrophysics: 347–356. arXiv:astro-ph/0401458Freely accessible. Bibcode:2004A&A...418..347M. doi:10.1051/0004-6361:20040025. Retrieved 21 April 2017. 
  6. ^ a b c Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923Freely accessible. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. Retrieved 19 October 2017. 
  7. ^ a b c d Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. Bibcode:2004PDSS...12.....T. Retrieved 19 October 2017. 
  8. ^ a b c Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522Freely accessible. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. Retrieved 19 October 2017. 
  9. ^ a b c Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 19 October 2017. 
  10. ^ a b Jim Baer (2008). "Recent Asteroid Mass Determinations". home.earthlink.net. Retrieved 2008-11-28. 
  11. ^ a b c d "LCDB Data for (65) Cybele". Asteroid Lightcurve Database (LCDB). Retrieved 21 April 2017. 
  12. ^ Warner, Brian D. (December 2007), "Initial Results of a Dedicated H-G Project", The Minor Planet Bulletin, 34, pp. 113–119, Bibcode:2007MPBu...34..113W 
  13. ^ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762Freely accessible. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 19 October 2017. 
  14. ^ "IAUC 3439: 1979l; Occn OF AGK3 +19 599 BY (65)". IAU – Central Bureau for Astronomical Telegrams. 4 January 1980. Retrieved 21 April 2017. 
  15. ^ Johnston, Robert (25 March 2017). "Asteroids with Satellites". johnstonsarchive.net. Retrieved 21 April 2017. 
  16. ^ Licandro, J.; Campins, H.; Kelley, M.; Hargrove, K.; Pinilla-Alonso, N.; Cruikshank, D.; et al. (January 2011). "(65) Cybele: detection of small silicate grains, water-ice, and organics". Astronomy and Astrophysics. 525: 7. Bibcode:2011A&A...525A..34L. doi:10.1051/0004-6361/201015339. Retrieved 21 April 2017. 
  17. ^ IOTA. "(65) Cybele 2008 Aug 24 profile". Retrieved 2010-12-02. 
  18. ^ Steve Preston. "(65) Cybele / 2UCAC 28838190 event on 2009 Oct 11, 01:30 UT". Retrieved 2009-09-21. [permanent dead link]

External links[edit]