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624 Hektor

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Title: 624 Hektor  
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Subject: Jupiter trojan, D-type asteroid, August Kopff, 588 Achilles, 617 Patroclus
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624 Hektor

624 Hektor
Star field showing Hektor (apmag 15)
Discovered by August Kopff
Discovery date 10 February 1907
Named after
1907 XM; 1948 VD
Jupiter trojan (leading cloud)
Adjectives Hektorian
Orbital characteristics[1]
Epoch 22 October 2004 (JD 2453300.5)
Aphelion 5.349 AU (800.220 Gm)
Perihelion 5.095 AU (762.145 Gm)
5.222 AU (781.183 Gm)
Eccentricity 0.024
11.93 a (4358.521 d)
Average orbital speed
13.03 km/s
Inclination 18.198°
Known satellites S/2006 (624) 1[2]
(diameter of 15 km)
Physical characteristics
Dimensions 370 × 195 × 195 km[3]
226.68 ± 15.15 km[4]
Mass (9.95 ± 0.12) × 1018 kg[4]
Mean density
1.0 ± 0.3 g/cm3[5]
1.63 ± 0.32 g/cm3[4]
2.43 ± 0.35 g/cm3[6]
~ 0.067 m/s²
~ 0.13 km/s
0.2884 d (6.92 h)[7]
Albedo 0.025 (geometric)[1]
Temperature ~ 122 K
Spectral type
13.79 to 15.26
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 1
  • Hektor in fiction 2
  • References 3
  • External links 4

Contact binary plus moon

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 because of a limited angular resolution. On 17 July 2006, the Keck 10-meter-II-telescope and its laser guide star adaptive optics (AO) system indicated a bilobate shape for Hektor.[8] Additionally, a 12-km-diameter moon of Hektor, S/2006 (624) 1, was detected orbiting with a semi-major axis of 623.5 km and an orbital period of 2.9651 day.[2][5] It was confirmed with Keck observations in November 2011.[9] 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.[8]

The largest Jupiter trojans
Trojan Diameter (km)
624 Hektor 225
911 Agamemnon 167
1437 Diomedes 164
1172 Äneas 143
617 Patroclus 141
588 Achilles 135
1173 Anchises 126
1143 Odysseus 126
Source: JPL Small-Body Database, IRAS data

Hektor in fiction


  1. ^ a b c "JPL Small-Body Database Browser: 624 Hektor (1907 XM)" (5 September 2008 last obs). Retrieved 1 November 2008. 
  2. ^ a b "IAUC 8732: S/2006 (624) 1 (Satellite Discovery)". Retrieved 23 July 2006. 
  3. ^ Storrs, Alex; Weiss, B.; Zellner, B. (1998). "Imaging Observations of Asteroids with Hubble Space Telescope" (PDF). Icarus 137 (2): 260–268.  
  4. ^ a b c Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science 73: 98–118,   See Table 1.
  5. ^ a b Marchis, Frank; Durech, Josef; Castillo-Rogez, Julie; Vachier, Frédéric; Ćuk, Matija; Berthier, Jérôme; Wong, Michael H.; Kalas, Paul; Duchene, Gaspard; van Dam, Marcos A.; Hamanowa, H.; Viikinkoski, M. (28 February 2014). "The Puzzling Mutual Orbit of the Binary Trojan Asteroid (624) Hektor" (PDF).  
  6. ^ Descamps, Pascal (2015). "Dumb-bell-shaped equilibrium figures for fiducial contact-binary asteroids and EKBOs". Icarus 245: 64–79.  
  7. ^ D, A.; Hainaut, O.; Pospieszalska-Surdej, A.; Schils, P.; Schober, H. J.; Surdej, J.; et al. (1994). "Pole, albedo and shape of the minor planets 624 Hektor and 43 Ariadne". Astronomy and Astrophysics 281: 269.  
  8. ^ a b Franck Marchis. "Searching and Characterizing Multiple Trojan Asteroids with LGS AO Systems" (PDF). 
  9. ^ "Tiny moon of (624) Hektor observed with Keck-AO NGS". 

External links

  • Orbital simulation from JPL (Java) / Ephemeris
  • Keck image of Hektor and moon (Marchis 2011-Nov-11)
  • Distant Asteroid Revealed to be a Complex Mini Geological World (2014 February 27)
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