Cubewano

A cubewano is also called traditional object of the belt of Kuiper or, in English, classical kuiper belt object (CKBO).

A cubewano is a member of a class of Astéroïde S evolving/moving in the Ceinture of Kuiper. The name was derived from the name of the first object of this class. The following objects of this class were initially named the QB1-bones, then cubewanos . Indeed, QB-1, in English, decides /kju: bwan/.

These objects remain at long distance from Neptune and are not in resonance with it. Their Orbite S remains nevertheless stable because they are almost circular, with the manner of the Planet S: it is this similarity with the planets which gave them the name of object traditional of the belt of Kuiper. Their average ray of revolution lies between 42 and 48 ua. The theory of their formation is identical to that of planets, by slow Accrétion of matter of the disc protoplanétaire. Nevertheless, the weak density of matter detected in this area leads certain scientists to imagine a formation of these objects closer to the Sun followed by a migration to their current location, following the proper migration of Neptune.

Some representatives of this family:

is the first transneptunien object discovered since Pluton and Charon.
(20000) Varuna (900 km) first large planetoid discovered in the belt.
(50000) Quaoar, which was the largest planetoid known until the discovery of (90377) Sedna in 2003.
which was the first known Objet transneptunien binary after the couple Pluto-Charon.
(58534) Logos planet doubles since its satellite Zoe (64 km diameter) is almost as massive as this planetoid 80 km in diameter.

Orbits

The diagram illustrates the orbits of large the cubiwanos beyond the orbits of broad the Plutino S (Pluton, (90482) Orcus and (28978) Ixion). The eccentricity of the orbits is represented by the segments (Périhélie with the Aphélie) with the Inclinaison represented on the vertical axis. (50000) Quaoar, for example, has a typical orbit, almost circular, (represented by a short red segment), near to the ecliptic . The plutinos on the other hand, have more eccentric orbits, bringing some of them more close to the Sun that Neptune (position marked with resonance 1:1).

The orbits of large the cubewanos are not representative of the whole of the family. The majority of the objects, the population known as cold , has orbits quasi-circulars and not very tilted. A population fewer, known as hot , is characterized by the strongly tilted orbits and more eccentrics.

Second diagram shows all the known cubewanos (March 2007). The Histogramme S present the distribution of the slope I (interval 5^o) and of the eccentricity E (interval 0,05) of the orbites¹. The great majority of the objects (more ²/₃) follows not very tilted orbits (i< 5^o and little eccentrics (e<0,1). The distribution of the half axes has , illustrates the preference for the medium of the principal belt; probably, the smallest objects too close to resonances either were captured in its resonances, or underwent modifications of their orbits by the action of Neptune.

¹Pour the comparison, the plutinos are represented on the graph (in gray) but are excluded from the statistics of the cubewanos.

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