Cordelia (moon)

Voyager 2 Richard John Terrile

Cordelia (also Uranus VI) is the innermost known and one of the smaller of the 27 known moons of the planet Uranus.

Discovery and designation

Cordelia was discovered on January 20, 1986 along with Ophelia by astronomer Richard John Terrile on photographic images of the Voyager 2 spacecraft. The discovery was announced on 27 January 1986 by the International Astronomical Union ( IAU); the moon first received the provisional designation S/1986 U 7

As Ophelia Cordelia was lost in the subsequent period. The astronomer Richard French from Wellesley College and Philip Nicholson of Cornell University searched for wave-like distortion in the shape of the Uranus rings which may be caused by the gravitational effect of the shepherd moons. The scientists found a wave- like pattern on one edge of Epsilonringes. Under the assumption that this would have ripples are in agreement with the orbital motions of Cordelia and Ophelia, they calculated their location. The calculated position for Ophelia was very close to the point where Erich Karkoschka ( Lunar and Planetary Laboratory, Tucson ) Ophelia had found. French and Nicholson delivered Karkoschka then a position for Cordelia. And as Karkoschka controlled the Hubble images in March 2000, he found Cordelia exactly where French had predicted. The two moons were found again.

Cordelia ( Latin for " the right heart " ) is in William Shakespeare's tragedy King Lear King's youngest daughter, who has a noble heart, and her father loves selflessly and sincerely.

All the moons of Uranus are named after characters from Shakespeare or Alexander Pope. The first four moons discovered Uranus ( Oberon, Titania, Ariel, Umbriel ) were proposed by John Herschel, the son of Uranus discoverer William Herschel, named. Later, the tradition of naming was retained.

Web properties

Orbit

Cordelia orbiting Uranus on a prograde, nearly perfectly circular orbit with an average distance of about 49,752 km from its center, ie 24,193 km above the cloud tops. This means that it is the surface closer than Uranus Uranus midpoint itself The orbital eccentricity of 0.00026, the orbit is inclined 0.08479 ° relative to the equator of Uranus.

The orbit of the next outer moon Ophelia is located in the central 4012 km of Cordelia's orbit. Cordelia is in the midst of two Uranus rings, the inner current δ (delta) - ring which is removed on average about 1452 km from the Cordelia - orbit, and the outer λ (lambda ) - dust ring in only 271 km away.

Cordelia moves as the inner shepherd moon within the brightest ε ( epsilon) - ring of Uranus, which is 1397 km away from Cordelia orbit, and influenced by their gravitational effect of the ring particles. The inner border of the ring is to Cordelia in a 24:25 - orbital resonance, the outer edge, it has some resonance from 14:13 to outer shepherd moon Ophelia. The masses of the two satellites must be at least three times the mass of the ring so that it can be effectively held in its limit. The mass of the ε - ring is estimated to be about 1016 kg. In addition, the sharp outer edge of the δ - ring has a 23:22 resonance with Cordelia.

Cordelia orbits Uranus in 8 hours, 2 minutes and 26.92 seconds. Since this is faster than the rotation of Uranus, Cordelia is seen from Uranus from the west, and set in the east.

It moves within a critical distance, near the Roche limit, in a descending orbit around the planet and will eventually be torn apart as a result of tidal forces into a ring or plunge into Uranus ' atmosphere or burn up.

Rotation

It is believed that Cordelia synchronously rotates and its axis having an inclination of 0 °.

Physical Properties

Cordelia has a mean diameter of 40.2 km. In the shots of the Voyager 2 probe Cordelia appeared as an elongated object with dimensions of 50 × 36 × 36 km, with the longitudinal axis is aligned with Uranus.

Its mean density is significantly lower than the density of the earth with 1.3 g / cm ³ and points out that the moon is composed mainly of water ice. It has a very low albedo of 0.08, that is, 8% of the incident solar light is reflected from the surface. It is thus a very dark celestial bodies. On its surface is the acceleration of gravity 0.0073 m / s ², which corresponds to less than 1 ‰ of the earth. The average surface temperature of Cordelia is estimated at -184 to -209 ° C ( 89-64 K).

Otherwise, not much is known about this moon since images of the probe came at a great distance and therefore have a low resolution.

Research

Since the flyby of the Voyager 2 spacecraft, the Uranus system of ground-based observations as well as the Hubble Space Telescope has been studied intensively. The orbital parameters of Cordelia could be clarified.