216 Kleopatra

216 Kleopatra
216 Kleopatra
216 Kleopatra.gif
(Animation)
Discovery
Discovered by Johann Palisa
Discovery date April 10, 1880
Designations
Named after Cleopatra VII
Alternate name(s) A905 OA, A910 RA
Minor planet
category
Main belt
Epoch 30 January 2005 (JD 2453400.5)
Aphelion 3.496 AU (523.049 Gm)
Perihelion 2.089 AU (312.544 Gm)
Semi-major axis 2.793 AU (417.796 Gm)
Eccentricity 0.252
Orbital period 4.67 a (1704.704 d)
Average orbital speed 17.82 km/s
Mean anomaly 55.259°
Inclination 13.136°
Longitude of ascending node 215.672°
Argument of perihelion 179.099°
Satellites 2
Physical characteristics
Dimensions 217 × 94 × 81 km
Mass 4.64 ± 0.02 × 10^18 kg [1]
Mean density 3.6
Rotation period 5.385 h
Albedo 0.116
Temperature unknown
Spectral type M
Absolute magnitude (H) 7.3

216 Kleopatra (play /ˌklɵˈpætrə/) 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.

Kleopatra has an unusual shape that has been compared to a dog's bone. This bilobate shape was revealed by adaptive optics on the ESO 3.6 m Telescope at La Silla, run by the European Southern Observatory. By bouncing radar signals off the asteroid, a team of astronomers at the Arecibo radio telescope in Puerto Rico were able to develop a more detailed computer model of its shape, which confirmed the earlier results.

Kleopatra is a relatively large asteroid, measuring 217 × 94 × 81 km. Calculations from its radar albedo and the orbits of its moons show it to be a rubble pile, a loose amalgam of metal, rock, and 30–50% empty space by volume, likely due to a disruptive impact prior to the impact that created its moons.

Satellite system

In September 2008, Franck Marchis and his collaborators announced that using the Keck Observatory's adaptive optics system, they had discovered two moons orbiting Kleopatra.[2] The outer and inner satellites are about 5 km and 3 km in diameter, respectively.[3]
In February 2011 they were named Alexhelios (/ˌælɨksˈhli.ɵs/, outer) and Cleoselene (/ˌklɵsɨˈln/, inner), after Cleopatra's children Alexander Helios and Cleopatra Selene II.[4]

It is believed that Kleopatra's odd shape, rotation, and moons are due to an oblique impact perhaps 100 million years ago. The increased rotation would have elongated the asteroid and caused Alexhelios to split off. Cleoselene may have split off around 10 million years ago. Thus Kleopatra may be a failed binary asteroid, very close to being a contact binary.[1]

References

External links


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Look at other dictionaries:

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  • (216) Клеопатра — У этого термина существуют и другие значения, см. Клеопатра (значения). (216) Клеопатра Астероид Клеопатра в представлении художника …   Википедия

  • Kleopatra (Asteroid) — Asteroid (216) Kleopatra Eigenschaften des Orbits ( …   Deutsch Wikipedia

  • (216) Cleopatra — Cleopatra Descubrimiento Descubridor Johann Palisa Fecha 10 de abril de 1880 …   Wikipedia Español

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