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

August Kopff

August Kopff was a German astronomer who discovered several comets and asteroids. He worked in Heidelberg, then joined the Humboldt University of Berlin where he became the Director of the Institute for Astronomical Calculation.He discovered some comets, including periodic comet 22P/Kopff and the...

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Hektor is a D-type asteroid

D-type asteroid

D-type asteroids have a very low albedo and a featureless reddish electromagnetic spectrum. It has been suggested that they have a composition of organic rich silicates, carbon and anhydrous silicates, possibly with water ice in their interiors...

, dark and reddish in colour. It lies in Jupiter's leading Lagrangian point

Lagrangian point

The Lagrangian points are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects...

, , called the 'Greek' node after one of the two sides in the legendary Trojan War

Trojan War

In Greek mythology, the Trojan War was waged against the city of Troy by the Achaeans after Paris of Troy took Helen from her husband Menelaus, the king of Sparta. The war is among the most important events in Greek mythology and was narrated in many works of Greek literature, including the Iliad...

. 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

617 Patroclus

617 Patroclus is a binary minor planet made up of two similarly-sized objects orbiting their common centre of gravity. It is a Trojan asteroid, sharing an orbit with Jupiter. It was discovered in 1906 by August Kopff, and was the second trojan to be discovered...

 in the Trojan node).

Contact binary plus moonlet

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

Contact binary (asteroid)

In the study of asteroids, a contact binary is caused when two asteroids gravitate toward each other until they touch, forming an oddly-shaped single body. Asteroids suspected of being contact binaries include the unusually elongated 624 Hektor and the bilobated 216 Kleopatra and 4769 Castalia...

 (two asteroids joined by gravitational attraction) like 216 Kleopatra

216 Kleopatra

216 Kleopatra is a trinary main-belt asteroid that was discovered by Johann Palisa on April 10, 1880, in Pola. It is named after Cleopatra, Queen of Ancient Egypt....

. Hubble Space Telescope

Hubble Space Telescope

The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...

 observations of Hektor in 1993 did not show an obvious bilobate shape because of a limited angular resolution

Angular resolution

Angular resolution, or spatial resolution, describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object...

. On 17 July 2006, the Keck

Keck telescopes

The W. M. Keck Observatory is a two-telescope astronomical observatory at an elevation of near the summit of Mauna Kea in Hawai'i. The primary mirrors of each of the two telescopes are in diameter, making them the second largest optical telescopes in the world, slightly behind the Gran Telescopio...

-10m II telescope and its Laser guide star

Laser guide star

Laser guide stars are a form of artificial star created for use in astronomical adaptive optics imaging.Adaptive optics systems require a wavefront reference source in order to correct atmospheric distortion of light...

 Adaptive Optics

Adaptive optics

Adaptive optics is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions. It is used in astronomical telescopes and laser communication systems to remove the effects of atmospheric distortion, and in retinal imaging systems to reduce the...

 (AO) system indicated a bilobate 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 moonlet at of Hektor's primary was detected. The satellite's provisional designation is S/2006 (624) 1. Hektor is, so far, the only known binary trojan asteroid in the point and the first trojan with a satellite companion. 617 Patroclus

617 Patroclus

617 Patroclus is a binary minor planet made up of two similarly-sized objects orbiting their common centre of gravity. It is a Trojan asteroid, sharing an orbit with Jupiter. It was discovered in 1906 by August Kopff, and was the second trojan to be discovered...

, another large trojan asteroid located in the , is composed of two same-sized components.

External links

• Orbital simulation from JPL (Java) / Ephemeris
• Keck image of Hektor and moon (Marchis 2011-Nov-11)