624 Hektor

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624 Hektor
Star field showing Hektor (apmag 15)
Discovered by August Kopff
Discovery date 10 February 1907
Pronunciation /ˈhɛktɔr/ HEK-tor
Named after Hector
Alternative names 1907 XM; 1948 VD
Minor planet category Trojan asteroid
Adjective Hektorian
Orbital characteristics[2]
Epoch 22 October 2004 (JD 2453300.5)
Aphelion 5.349 AU (800.220 Gm)
Perihelion 5.095 AU (762.145 Gm)
Semi-major axis 5.222 AU (781.183 Gm)
Eccentricity 0.024
Orbital period 11.93 a (4358.521 d)
Average orbital speed 13.03 km/s
Mean anomaly 94.752°
Inclination 18.198°
Longitude of ascending node 342.791°
Argument of perihelion 183.579°
Known satellites S/2006 (624) 1[1]
(15km diameter)
Physical characteristics
Dimensions 370 × 195 × 195 km[3]
226.68 ± 15.15[4] km
Mass (9.95 ± 0.12) × 1018[4] kg
Mean density 1.63 ± 0.32[4] g/cm3
Equatorial surface gravity ~0.067 m/s²
Escape velocity ~0.13 km/s
Rotation period 0.2884 d (6.92 h)[5]
Albedo 0.025 (geometric)[2]
Temperature ~122 K
Spectral type D
Apparent magnitude 13.79 to 15.26
Absolute magnitude (H) 7.49[2]
Angular diameter 0.078" to 0.048"

624 Hektor is the largest Jupiter trojan. It was discovered in 1907 by August Kopff.

Hektor is a D-type asteroid, dark and reddish in colour. It lies in Jupiter's leading Lagrangian point, L4, called the 'Greek' node after one of the two sides in the legendary Trojan War. Hektor is named after the Trojan hero Hektor and is thus one of two trojan asteroids that is "misplaced" in the wrong camp (the other one being 617 Patroclus in the Trojan node).

Contact binary plus moon[edit]

Hektor is one of the most elongated bodies of its size in the Solar System, being 370 × 200 km. It is thought that Hektor might be a contact binary (two asteroids joined by gravitational attraction) like 216 Kleopatra. Hubble Space Telescope observations of Hektor in 1993 did not show an obvious bilobate shape[citation needed] because of a limited angular resolution. On 17 July 2006, the Keck-10m II telescope and its Laser guide star Adaptive Optics (AO) system indicated a bilobate shape for Hektor.[6] Additionally, a 15-km moon at 1000 km of Hektor, S/2006 (624) 1, was detected.[1] and was confirmed with Keck observations in November 2011.[7] Hektor is, so far, the only known binary trojan asteroid in the L4 point and the first known trojan with a satellite companion. 617 Patroclus, another large trojan asteroid located in the L5, is composed of two same-sized components.[6]

Hektor in fiction[edit]

See Asteroids in fiction.


  1. ^ a b "IAUC 8732: S/2006 (624) 1 (Satellite Discovery)". Retrieved 23 July 2006. 
  2. ^ a b c "JPL Small-Body Database Browser: 624 Hektor (1907 XM)". 5 September 2008 last obs. Retrieved 1 November 2008. 
  3. ^ Storrs, Alex; Weiss, B.; Zellner, B. et al. (1998). "Imaging Observations of Asteroids with Hubble Space Telescope". Icarus 137 (2): 260–268. Bibcode:1999Icar..137..260S. doi:10.1006/icar.1999.6047. Retrieved 22 May 2008. 
  4. ^ a b c Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science 73: 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009.  See Table 1.
  5. ^ Detal, A.; Hainaut, O.; Pospieszalska-Surdej, A.; Schils, P.; Schober, H. J.; Surdej, J. (1994). "Pole, albedo and shape of the minor planets 624 Hektor and 43 Ariadne". Astronomy and Astrophysics 281: 269. Bibcode:1994A&A...281..269D. ISSN 0004-6361. 
  6. ^ a b Franck Marchis. "Searching and Characterizing Multiple Trojan Asteroids with LGS AO Systems". 
  7. ^ "Tiny moon of (624) Hektor observed with Keck-AO NGS". 

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