624 Hektor

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624 Hektor
Discovery
Discovered by August Kopff
Discovery time February 10, 1907
Names
Other names 1907 XM; 1948 VD
Group Trojan asteroid
Orbit
Reference date October 22, 2004 (JD 2453300.5)
Longest distance from the Sun 800.220 Gm (5.349 AU)
Shortest distance from the Sun 762.145 Gm (5.095 AU)
Longest distance from the center of its orbital path
("semi-major axis")
781.183 Gm (5.222 AU)
How egg-shaped its orbit is
("eccentricity")
0.024
How long it takes to complete an orbit 4358.521 d (11.93 a)
Average speed 13.03 km/s
Mean anomaly 94.752°
Angle above the reference plane
("inclination")
18.198°
Longitude of where it comes up through the reference plane 342.791°
Angle between its shortest distance from what it orbits around and where it comes up through the reference plane
("argument of periapsis")
183.579°
Size and Other Qualities
Measures 370 × 195 km
Mass ~1.4×1019 kg
Average density 2 ? g/cm³
Gravity at its surface ~0.067 m/s²
Slowest speed able to escape into space
("escape velocity")
~0.13 km/s
How long it takes to turn around one time 0.2884 d (6.92 h)[1]
How much light it reflects 0.025 (geometric[2]
Avg. surface temp. ~122 K
Light-band group
("spectral type")
D
Seeming brightness
("apparent magnitude")
13.79 to 15.26
True brightness
("absolute magnitude")
7.49
Seeming size
("angular diameter")
0.078" to 0.048"

624 Hektor is the biggest of the Jovian Trojan asteroids. It was found 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. Ironically, 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 being 617 Patroclus in the Trojan node).

Hektor is one of the most stretched 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 sightings of Hektor in 1993 did not show an obvious stretched shape because of a limited angular resolution. On July 17, 2006, the Keck-10m II telescope and its Laser guide star Adaptive Optics (AO) system indicated a stretched shape for Hektor. Additionally, since this AO system provides an excellent and stable correction (angular resolution of 0.060 arcsec in K band), a 15-km moon at 1000 km from Hektor was found. The moon's provisional designation is S/2006 (624) 1.[3] Hektor is, so far, the only known binary Trojan asteroid in the L4 point and the first Trojan with a moon. 617 Patroclus, another big Trojan asteroid located in the L5, is made of two same-sized asteroids.

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