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 Brown's website lists it as possibly a dwarf planet with a measured diameter of 232 km.

Discovery and naming

Chariklo was discovered by James V. Scotti of the

Spacewatch The Spacewatch Project is an astronomical survey that specializes in the study of minor planets, including various types of asteroids and comets at University of Arizona telescopes on Kitt Peak near Tucson, Arizona, in the United States. The Sp ...

program on February 15, 1997. Chariklo is named after the

nymph A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are ty ...

Chariclo Chariclo ( or ; grc, Χαρικλώ, Khariklṓ, graceful spinner) is either of two nymphs in Greek mythology: * Chariclo, a nymph who was married the centaur Chiron and became the mother of Hippe, Endeïs, Ocyrhoe, and Carystus. In some accounts ...

('), the wife of

Chiron In Greek mythology, Chiron ( ; also Cheiron or Kheiron; ) was held to be the superlative centaur amongst his brethren since he was called the "wisest and justest of all the centaurs". Biography Chiron was notable throughout Greek mythology ...

and the daughter of

Apollo Apollo, grc, Ἀπόλλωνος, Apóllōnos, label=genitive , ; , grc-dor, Ἀπέλλων, Apéllōn, ; grc, Ἀπείλων, Apeílōn, label=Arcadocypriot Greek, ; grc-aeo, Ἄπλουν, Áploun, la, Apollō, la, Apollinis, label= ...

. A symbol derived from that for

2060 Chiron 2060 Chiron is a small Solar System body in the outer Solar System, orbiting the Sun between Saturn and Uranus. Discovered in 1977 by Charles Kowal, it was the first-identified member of a new class of objects now known as centaurs—bodies orb ...

, 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

is likely to be the third largest with .

Orbit

Centaurs originated in the

Kuiper belt The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...

and are in dynamically unstable orbits that will lead to ejection from the Solar System, an

impact Impact may refer to: * Impact (mechanics), a high force or shock (mechanics) over a short time period * Impact, Texas, a town in Taylor County, Texas, US Science and technology * Impact crater, a meteor crater caused by an impact event * Impact ...

with a planet or the Sun, or transition into a short-period

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...

. The orbit of Chariklo is more stable than those of Nessus,

, and Pholus. Chariklo lies within 0.09 AU of the 4:3

resonance Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillatin ...

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 perihelic

opposition Opposition may refer to: Arts and media * ''Opposition'' (Altars EP), 2011 EP by Christian metalcore band Altars * The Opposition (band), a London post-punk band * ''The Opposition with Jordan Klepper'', a late-night television series on Comed ...

s of 2003–04, Chariklo had an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

of +17.7. , Chariklo was 14.8 AU from the Sun. Animation of Chariklo orbit

Rings

A stellar

in 2013 revealed that Chariklo has two

ring 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 ...

s 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 moon A shepherd moon (also herder moon or watcher moon) is a small natural satellite that clears a gap in planetary-ring material or keeps particles within a ring contained. The name is a result of the fact they limit the "herd" of the ring particle ...

s 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 Haumea (minor-planet designation 136108 Haumea) is a dwarf planet located trans-Neptunian object, beyond Neptune's orbit. It was discovered in 2004 by a team headed by Michael E. Brown, Mike Brown of Caltech at the Palomar Observatory in the United ...

. The team nicknamed the rings

(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

IAU The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...

at a later date. It has been speculated that

may have a similar pair of rings.

Exploration

''Camilla'' is a mission concept published in June 2018 that would launch a robotic probe to perform a single flyby of Chariklo and drop off a impactor made of

tungsten Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolat ...

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 The New Frontiers program is a series of space exploration missions being conducted by NASA with the purpose of furthering the understanding of the Solar System. The program selects medium-class missions which can provide high science returns. ...

, 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 010199 Named minor planets 010199 010199 19970215