Trinculo (moon)

Trinculo
Discovery picture from Trinculo, 2001
Provisional or systematic name	S / 2001 U 1
Central body	Uranus
Properties of the orbit
Major semi-axis	8,501,260 km
Periapsis	6,650,240 km
Apoapsis	10,352,280 km
eccentricity	0.2177350
Orbit inclination	(to the ecliptic ) 166.25279 °
Orbital time	748.83 d
Mean orbital velocity	0.82 km / s
Physical Properties
Albedo	≈ 0.04-0.07
Apparent brightness	25.4 mag
Medium diameter	≈ 18 km
Dimensions	≈ 7.85 · 10 14 to 3.9 · 10 15 kg
surface	≈ 3,000 km 2
Medium density	≈ 1.3-1.5 g / cm 3
Acceleration of gravity on the surface	0.0021 m / s 2
Surface temperature	≈ −184 to −208 ° C; 89-65 K
discovery
Explorer	Matthew J. Holman , John J. Kavelaars , Dan Milisavljevic , Brett J. Gladman
Date of discovery	August 13, 2001
Remarks	Physical data relatively imprecise

Trinculo (also Uranus XXI ) is the sixth outermost of the 27 known and fourth innermost of the outer retrograde irregular moons of the planet Uranus . It is one of the smallest, if not the smallest, of the planet's natural satellites.

Discovery and naming

Trinculo was discovered on August 13, 2001 by a team of astronomers Matthew J. Holman , John J. Kavelaars , and Dan Milisavljevic . The recordings were made with the 4-meter Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile . It was the first Uranus moon to be discovered in the 21st century. Soon after the recordings, which also showed Francisco , Ferdinand and actually Margaret , the astronomers unfortunately lost track of the moon again. As the orbit could therefore not be secured, the International Astronomical Union decided not to publish the discovery. It was Brett J. Gladman who found Trinculo on September 5, 2002 footage from the Paranal Observatory in Chile. Matthew Holman and Tommy Grav then confirmed the rediscovery through recordings on the CTIO on August 13, 2002. The discovery was announced on September 30, 2002; the moon was initially given the provisional designation S / 2001 U 1 .

On August 8, 2003 the moon was officially named Trinculo, like all irregular Uranus moons except Margaret after a figure in William Shakespeare's The Storm . Trinculo is a drunken fool who initially plans with Caliban and Stephano to kill the magician Prospero , but Trinculo later decides to only join someone he can be his own master with.

So far, all Uranus moons have been named after characters from Shakespeare or Alexander Pope . The first four Uranus moons discovered, Oberon , Titania , Ariel and Umbriel , were named after suggestions by John Herschel , the son of the Uranus discoverer Wilhelm Herschel . Later the tradition of naming was retained.

The provisional designation S / 2001 U 1 corresponds to the system of the International Astronomical Union (IAU).

Track properties

Classification in the irregular moons

Trinculo orbits Uranus on a retrograde , relatively slightly elliptical orbit for an irregular moon between 6,650,240 and 10,352,280 km from its center ( major orbit half-axis 8,501,260 km or 332,613 Uranus radii), i.e. around 8,475,700 km above its cloud ceiling. The orbital eccentricity is 0.2177350, the web is 166.25279 ° relative to the ecliptic inclined . Trinculo is over 14 times as far from Uranus as the outermost regular moon Oberon .

Due to the great distance to Uranus and gravitational disturbances from the sun and other factors, the orbit parameters are possibly variable; the moon could perhaps also enter a heliocentric orbit (again). The eccentricity is therefore also given between 0.2079 and 0.2200, the orbit inclination (compared to the ecliptic) between 166.971 ° and 167.05 ° and the major orbit half-axis between 8.002 and 8.505 million km. Trinculo's orbit is relatively circular for an irregular moon.

Trinculo is a member of the Caliban group , a subgroup of irregular moons with moderate eccentricity and high orbital inclinations between 140 ° and 170 °, to which Francisco , Caliban and Stephano also belong. Within this group, Trinculo is the only one that stands out due to the approximately 20 ° higher inclination of the orbit and thus represents a dynamic group of its own.

The orbit of the next inner moon Stephano is on average about 800,000 km from Trinculos orbit, the distance of the orbit of the next outer moon Sycorax is on average about 3.67 million km.

Trinculo orbits Uranus in around 748 days, 19 hours and 55 minutes, or around 2,050 earth years. The orbital period is also given as 749.24 and 749.40 days. Trinculo needs almost as long to orbit Uranus as the planet Mars does around the sun.

Physical Properties

Trinculo has an estimated diameter of 18 km (according to other information 10 km), based on the assumed reflectivity of 4%, which can, however, also be 7%. In any case, the surface is extremely dark. Trinculo is most likely the smallest known Uranus moon, its size could only be undercut by the Cupid discovered in 2003 . In any case, it is the faintest moon in the entire Uranus system . Trinculo's density is estimated to be between 1.3 and 1.5 g / cm ³ . The moon is therefore likely to be composed mainly of water ice and silicate rock. On its surface, the acceleration due to gravity is 0.0021 m / s ² , which corresponds to about 2 ‰ of that on earth. Trinculo appears in the spectrum in gray color.

Emergence

Trinculo is believed to be a trapped object of the Kuiper Belt and not arose in the accretion disk that formed the uranium system. It is conceivable that the moon first went from a Kuiper belt object to a centaur and was then captured by Uranus. The exact trapping mechanism is unknown, but trapping a moon requires dissipating energy. The hypotheses range from the entry of gas into the protoplanetary disk , interactions in the context of the multibody problem and capture by the rapidly increasing mass of Uranus.

exploration

Due to the great distance to Uranus and the weak brightness of 25.4 mag, which is 1: 91,200,000 compared to the central planet, Trinculo was not found when the Voyager 2 space probe flew by in 1986. Since the first discovery in 2001 and the rediscovery in 2002, Trinculo could only be observed through earth-based telescopes and its orbital elements and its brightness could be determined.

Web links

• IAUC 7980: S / 2001 U 1 September 30, 2002 (discovery)
• IAUC 8177: Satellites of Jupiter, Saturn, Uranus August 8, 2003 (designation)
• Polish moon page: Trinculo description and further links (English)

Individual evidence

1. ^ IAU: Natural Satellites Ephemeris Service. IAU Minor Planet Center, accessed February 12, 2011 .