90 Antiope

Orbital characteristics 1
Orbit type	Main belt (Themis)
Semimajor axis	3.157 AU
Perihelion distance	2.665 AU
Aphelion distance	3.649 AU
Orbital period	5.61 years
Inclination	2.22°
Eccentricity	0.156
Physical characteristics
Diameter 3	85, 85 km
Rotation period 3	16.496 hours (sync.)
Spectral class 1	C
Abs. magnitude 1	8.27
Albedo 4	0.060
History 2
Discoverer	R. Luther, 1866
Satellites
Designation	S/2000 (90) 1

90 Antiope (an-tye'-a-pee) is an asteroid discovered on October 1, 1866 by Robert Luther. The 90th asteroid to be discovered, it is named after a character in Greek Mythology, called Antiope, though it is disputed as to which, there being more than one.

Antiope is classified as a member of the Themis family of asteroids.

One observed stellar occultation by Antiope has been reported, on (June 11, 1980).

In 2000, using adaptive optics at the Keck Telescope on Mauna Kea it was discovered that Antiope is in fact a double asteroid, consisting of two individual bodies separated by 170 kilometers, orbiting around a common center. Additional studies by [lightcurve] variation and [adaptive optics] at [ESO]-[VLT] indicate that the lobes, approximated to a 80 kilometers diameter sphere, revolve around the center of mass in ~16.5 hours. Using the 3rd Kepler's law, the mass and density of the components can be derived. The relatively low density (0.6 ± 0.2 g/cm3) suggests a high porosity (>60%). Their composition is C-type, which means that they are dark in colouring with a carbonate composition.

External links

• SWrI Press Release
• Data from Johnston's Archive
• orbit of this binary system - results and simulatiosn