10199 Chariklo is the largest confirmed

centaur A centaur ( ; grc, κένταυρος, kéntauros; ), or occasionally hippocentaur, is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse. Centaurs are thought of in many Greek myths as being ...

(small body of the outer Solar System). It orbits the Sun between

Saturn Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...

and

Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...

, grazing the orbit of Uranus. On 26 March 2014, astronomers announced the discovery of two

rings Ring may refer to: * Ring (jewellery), a round band, usually made of metal, worn as ornamental jewelry * To make a sound with a bell, and the sound made by a bell :(hence) to initiate a telephone connection Arts, entertainment and media Film and ...

(nicknamed as the rivers

Oiapoque Oiapoque () is a municipality in the north of the state of Amapá, Brazil. Its population is 27,906 and its area is . Oiapoque is also a major river in the same state, forming the international border with French Guiana. The Oyapock River Bridge, c ...

and

Chuí Chuí () is a municipality located in the state of Rio Grande do Sul, Brazil. It's the southernmost municipality of Brazil, located in the coordinates 33°41′0″S . A border town, it shares its name with sister city Chuy, Uruguay. The two town ...

) around Chariklo by observing a stellar

occultation An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks ...

, making it the first

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...

known to have rings. A photometric study in 2001 was unable to find a definite period of rotation. Infrared observations of Chariklo indicate the presence of water ice, which may in fact be located in its rings. Michael E. Brown, Michael Brown's website lists it as List of possible dwarf planets, possibly a dwarf planet with a measured diameter of 232 km.

Discovery and naming

Chariklo was discovered by James V. Scotti of the Spacewatch program on February 15, 1997. Chariklo is named after the nymph Chariclo ('), the wife of Chiron and the daughter of Apollo. A symbol derived from that for 2060 Chiron, file:Chariklo symbol.svg, x14px, was devised in the late 1990s by German astrologer Robert von Heeren. It replaces Chiron's K with a C for Chariklo.

Size and shape

Chariklo is currently the largest known

, with a volume-equivalent diameter of about 250 km. Its shape is probably elongated with dimensions 287.6 × 270.4 × 198.2 km. is likely to be the second largest with and 2060 Chiron is likely to be the third largest with .

Orbit

Centaurs originated in the Kuiper belt and are in dynamically unstable orbits that will lead to ejection from the Solar System, an Impact event, impact with a planet or the Sun, or transition into a short-period comet. The orbit of Chariklo is more stable than those of 7066 Nessus, Nessus, 2060 Chiron, Chiron, and 5145 Pholus, Pholus. Chariklo lies within 0.09 Astronomical unit, AU of the 4:3 Orbital resonance, resonance of Uranus and is estimated to have a relatively long orbital half-life of about 10.3 Myr. Orbital simulations of twenty clones of Chariklo suggest that Chariklo will not start to regularly come within 3 AU (450 Gm) of Uranus for about thirty thousand years. During the Apsis, perihelic Opposition (planets), oppositions of 2003–04, Chariklo had an apparent magnitude of +17.7. , Chariklo was 14.8 Astronomical unit, AU from the Sun. Animation of Chariklo orbit

Rings

A stellar

in 2013 revealed that Chariklo has two planetary ring, rings with radii 386 and 400 km and widths of about 6.9 km and 0.12 km respectively. The rings are approximately 14 km apart. This makes Chariklo the smallest known object to have rings. These rings are consistent with an edge-on orientation in 2008, which can explain Chariklo's dimming before 2008 and brightening since. Nonetheless, the elongated shape of Chariklo explains most of the brightness variability resulting in darker rings than previously determined. Furthermore, the rings can explain the gradual disappearance of the water-ice features in Chariklo's spectrum before 2008 and their reappearance thereafter if the water ice is in Chariklo's rings. The existence of a ring system around a minor planet was unexpected because it had been thought that rings could only be stable around much more massive bodies. Ring systems around minor bodies had not previously been discovered despite the search for them through direct imaging and stellar occultation techniques. Chariklo's rings should disperse over a period of at most a few million years, so either they are very young, or they are actively contained by shepherd moons with a mass comparable to that of the rings. However, other research suggests that Chariklo's elongated shape combined with its fast rotation can clear material in an equatorial disk through Lindblad resonances and explain the survival and location of the rings, a mechanism valid also for the ring of Haumea. The team nicknamed the rings Oiapoque River, Oiapoque (the inner, more substantial ring) and

(the outer ring), after the two rivers that form the northern and southern coastal borders of Brazil. A request for formal names will be submitted to the International Astronomical Union, IAU at a later date. It has been speculated that 2060 Chiron may have Rings of Chiron, a similar pair of rings.

Exploration

Camilla (spacecraft), ''Camilla'' is a mission concept published in June 2018 that would launch a robotic probe to perform a single Planetary flyby, flyby of Chariklo and drop off a impactor made of tungsten to excavate a crater approximately deep for remote compositional analysis during the flyby. The mission would be designed to fit under the cost cap of NASA New Frontiers program, although it has not been formally proposed to compete for funding. The spacecraft would be launched in September 2026, using one gravity assist from Venus in February 2027 and Earth in December 2027 and 2029 to accelerate it out toward Jupiter.

References

External links

* 37th DPS
Albedos, Diameters (and a Density) of Kuiper Belt and Centaur Objects

(February 1999) * Chariklo'
orbit
between Saturn and Uranus.
Demonstration of how centaur 10199 Chariklo is currently controlled by Uranus
(Solex 10) * * {{DEFAULTSORT:Chariklo Centaurs (small Solar System bodies) Discoveries by James V. Scotti Discoveries by the Spacewatch project, 010199 Named minor planets Possible dwarf planets, 010199 D-type asteroids (SMASS), 010199 Astronomical objects discovered in 1997, 19970215