Ophelia (moon)

Ophelia is a moon of Uranus. It was discovered from the images taken by Voyager 2 on January 20, 1986, and was given the temporary designation S/1986 U 8.^[1] It was not seen again until the Hubble Space Telescope recovered it in 2003.^[7][9] Ophelia was named after the daughter of Polonius, Ophelia, in William Shakespeare's play Hamlet. It is also designated Uranus VII.^[10]

Ophelia

Ophelia (top), Cordelia (bottom), and Uranus's narrow rings photographed from afar by Voyager 2 on 21 January 1986
Discovery[1]
Discovered by	Richard J. Terrile / Voyager 2
Discovery date	January 20, 1986
Designations
Designation	Uranus VII
Pronunciation	/oʊˈfiːliə/[2]
Adjectives	Ophelian /ɒˈfiːliən/[3]
Orbital characteristics[4]
Semi-major axis	53763.390±0.847 km
Eccentricity	0.00992±0.000107
Orbital period (sidereal)	0.37640039±0.00000357 d
Average orbital speed	10.39 km/s[a]
Inclination	0.10362°±0.055° (to Uranus's equator)[4]
Satellite of	Uranus
Group	ring shepherd
Physical characteristics
Dimensions	54 × 38 × 38 km[5][note 1]
Surface area	~5900 km2[a]
Volume	40800±50.4% km3[6]
Mass	(3.57±0.32)×1016 kg[6]
Mean density	0.87+0.89 −0.30 g/cm3[6]
Surface gravity	~0.003–0.007 m/s2[a]
Escape velocity	~0.013–0.016 km/s[a]
Synodic rotation period	synchronous[5]
Axial tilt	zero[5]
Albedo	0.065±0.01[7] 0.07[8]
Temperature	~65 K[a]
Only two dimensions are known; the third dimension has been assumed to equal the smaller known dimension.

Other than its orbit,^[4] size of 54 km × 38 km (34 mi × 24 mi),^[5] and geometric albedo of 0.065,^[7] little is known about it. In images taken by Voyager 2, Ophelia appears as an elongated object, with its major axis pointing towards Uranus. The ratio of axes of the Ophelia's prolate spheroid is 0.7 ± 0.3.^[5]

Ophelia acts as the outer shepherd satellite for Uranus's ε ring.^[11] The orbit of Ophelia is within the synchronous orbit radius of Uranus, and is therefore slowly decaying due to tidal forces.^[5]

See also

• Moons of Uranus

Notes

1. Calculated on the basis of other parameters.