Ferdinand (moon)

Matthew J. Holman, John J. Kavelaars, Dan Milisavljevic, Brett J. Gladman, Scott S. Sheppard, David C. Jewitt

Ferdinand (also Uranus XXIV) is the outermost of the 27 known and the outermost irregular moon of the planet Uranus. He is one of the smaller natural satellite of the planet.

Discovery and designation

Ferdinand was discovered on 13 August 2001 by a team of astronomers Matthew J. Holman, John J. Kavelaars, Dan and Brett J. Gladman Milisavljevic on photographic shots at about the same time as the innermost known moon Uranus Francisco. The images were taken by the 4.0 -meter Blanco telescope at the Cerro Tololo Inter- American Observatory in Chile. Soon after the shooting, on which also Francisco, Trinculo and actually Margaret were to be seen, astronomers unfortunately lost the track of the moon again, although he on other recordings of 21 September and 15 November, and even a year later on 13 August and September 5, 2002 was to be seen. Since the orbit therefore could not be saved, the International Astronomical Union decided not to publish the discovery. It was Scott S. Sheppard, the Ferdinand on 24 September 2003 on recordings from 29 to 30 August at the 8.2-meter Subaru telescope, and 20 September 2003 with the 8.1 -meter Gemini - reflecting telescope (both in Hawaii) by David C. Jewitt and tracked him self again. On September 30, Matthew Holman made ​​observations to confirm on the Las Campanas Observatory, Chile. The discovery was announced on 1 October 2003; the moon first received the provisional designation S/2001 U 2

On 29 December 2005 the moon has then received the official name of Ferdinand, like all irregular moons of Uranus except Margaret, after a figure in William Shakespeare's The Tempest. Ferdinand was the son of Alonso, King of Naples. Ferdinand Prospero's daughter Miranda eventually marries and helps his father to regain his lost duchy of Milan.

So far, 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.

The provisional designation S/2001 U 2 corresponds to the classification of the International Astronomical Union ( IAU).

Web properties

Ferdinand Uranus rotates on a retrograde, highly elliptical orbit 11663850-29350350 km from its center ( Large semi-major axis 20.5071 million km or 802.344 Uranus radii ), or about 20.4815 million km on whose cloud tops. The orbital eccentricity of 0.4312285, the orbit is inclined 167.34637 ° to the ecliptic. Ferdinand is about 35 times as far from Uranus as the outermost regular moon Oberon.

Due to the large distance to Uranus and gravitational disturbances caused by the sun and other factors, the orbital parameters are thus possibly variable; the moon could perhaps get ( back ) into a heliocentric orbit. The eccentricity is therefore 0.3682 to 0.3993, the orbital inclination ( with respect to the ecliptic ) between 169.793 and 169.840 ° ° and the Great semi-major axis between 20,430 und 20.901 million kilometers indicated.

Ferdinand is a member of Sycorax group, a subgroup of the irregular moons with very high eccentricity and high orbital inclinations of 140 to 170 °, which also Sycorax, Prospero and Setebos belong. Within this group, Ferdinand falls as the only but due to the higher by about 20 ° orbital inclination, and thus constitutes its own dynamic group

The orbit of the next inner moon Setebos is about 3.09 million kilometers away from Ferdinand's orbit in the middle.

Ferdinand revolves around Uranus in 2805 days 12 hours and 14 minutes or about 7,681 Earth years. The orbital period is also specified with 2790.03 to 2887.21 days. Ferdinand thus requires more than half of the orbital period of the planet Jupiter around the Sun to orbit Uranus.

Physical Properties

Ferdinand has a diameter estimated at 21 km ( according to other sources 20 km), based on the assumed for him albedo of 4 %, which may be as well as 7%. The surface is thus in any case very dark. Its density is estimated to be between 1.3 and 1.5 g/cm3. So the moon is likely to be composed predominantly of water ice and silicate rock. On its surface, the gravitational acceleration is 0.0025 m/s2, this corresponds to about 2 ‰ of the earthly. Ferdinand appears in the spectrum in gray.

Formation

It is believed that Ferdinand is a captured Kuiper belt object and is not in the accretion disk that formed the Uranus system emerged. It is conceivable that the moon of a Kuiper Belt object first became a centaur and was subsequently captured by Uranus. The exact trapping mechanism is not known, but the entrapment of a moon requires the dissipation of energy. The hypotheses range from withdrawal of gas from the protoplanetary disk, interactions within the framework of the multi- body problem and capture by the strongly growing mass of Uranus.

Research

Because of the great distance to Uranus and weak brightness of 25.1 like the 1:69200000 is opposite to the central planet, Ferdinand was 2 1986 not found during the flyby of the Voyager spacecraft. Since the discovery in 1999 Ferdinand was observed, while its orbital elements and its brightness can be determined only by ground-based telescopes.

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