In astronomy a cubewano (pronounced /kjuːbiːwənoʊ/) is a Kuiper belt object that orbits beyond Neptune and is not controlled by an orbital resonance with the giant planet. Cubewanos have semi-major axes in the 40-50 AU range and, unlike Pluto, do not cross Neptune’s orbit. They are also called classical Kuiper Belt objects. The centaurs are a class of icy planetoids that orbit the Sun between Jupiter and Neptune, named after the mythical race of centaurs. ... As of June 2006, there are four[1] known Trojan asteroids of Neptune which have the same orbital period as the planet. ... A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ... In astronomy, a resonant Trans-Neptunian Object is a Trans-Neptunian Object (TNO) in mean motion orbital resonance with Neptune. ... In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ... The scattered disc (or scattered disk) is a distant region of our solar system, thinly populated by icy planetoids known as scattered disk objects (SDOs), a subset of the broader family of trans-Neptunian objects (TNOs). ... This image is an artists rendering of the Oort cloud and the Kuiper Belt. ... Symbols of the International Phonetic Alphabet. ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... Atmospheric characteristics Surface pressure ≫100 MPa Hydrogen - H2 80% ±3. ... In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... In geometry, the semi-major axis (also semimajor axis) a applies to ellipses and hyperbolas. ... The astronomical unit (AU or au or a. ... Adjectives: Plutonian Atmosphere Surface pressure: 0. ...

The odd name derives from the first trans-Neptunian object (TNO) found (besides Pluto and Charon), (15760) 1992 QB₁. Later objects were called "QB1-o's", or cubewanos. A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ... Charon (shair-É™n or kair-É™n (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... (15760) 1992 QB1 (also written (15760) 1992 QB1) was the first trans-Neptunian object to be discovered after Pluto and Charon. ...

Objects identified as cubewanos include:

• (15760) 1992 QB₁
• (136472) 2005 FY₉ the largest known cubewano and one of the largest TNO
• (136108) 2003 EL₆₁, notable for its elongated shape, two moons and rapid rotation (3.9h)
• (50000) Quaoar and (20000) Varuna, each considered the largest TNO at the time of discovery
• 2002 TX₃₀₀, 2002 AW₁₉₇, 2002 UX₂₅

This diagram illustrates the orbits of the larger or brighter cubewanos, with the larger plutinos (Pluto, Orcus and Ixion) plotted in grey for comparison. The horizontal axis represents the semi-major axes. The eccentricities of the orbits are represented by red segments (extending from perihelion to aphelion) with the inclinations represented on the vertical axis.

(15760) 1992 QB1 (also written (15760) 1992 QB1) was the first trans-Neptunian object to be discovered after Pluto and Charon. ... (136472) 2005 FY9 (also written (136472) 2005 FY9) is a very large Kuiper belt object discovered on March 31, 2005 by the team led by Michael Brown. ... (136108) 2003 EL61 (also written (136108) 2003 EL61), is a large (roughly one-third the mass of Pluto) and very unusual Kuiper belt object discovered by Mike Brown at Caltech in the United States. ... This article is about the trans-Neptunian object. ... (Redirected from (20000) Varuna) 20000 Varuna (VAR oo na) is a Kuiper Belt object about 1060 kilometers in diameter, estimated from a combination of thermal and optical measurements. ... (55636) 2002 TX300 (Also written as (55636) 2002 TX300) is a large Trans-Neptunian object discovered in October 15, 2002 by the NEAT program. ... (55565) 2002 AW197 (also written: (55565) 2002 AW197) is a trans-Neptunian object. ... (55637) 2002 UX25 (also written as (55637) 2002 UX25) is a large Trans-Neptunian object discovered on October 30, 2002 by the Spacewatch program. ... Adjectives: Plutonian Atmosphere Surface pressure: 0. ... 90482 Orcus (originally known by the provisional designation 2004 DW) is a Kuiper Belt object (KBO) that was discovered by Michael Brown of Caltech, Chad Trujillo of the Gemini Observatory, and David Rabinowitz of Yale University. ... (28978) Ixion (ik·sye·un) is a Kuiper belt object discovered on May 22, 2001 with a diameter of < 822 km and a semimajor axis of about 39. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ...

Orbits

Most cubewanos are found between the 2:3 orbital resonance with Neptune (populated by plutinos) and the 1:2 resonance. 50000 Quaoar, for example, has a near circular orbit close to the ecliptic. Plutinos, on the other hand, have more eccentric orbits bringing some of them closer to the Sun than Neptune. In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ... Artists impression by G. Bacon of STScI / NASA 50000 Quaoar (pronounced kwah·war, kwah·wor, or kwow·ur, Tongva ) [1] is a Trans-Neptunian object orbiting the Sun in the Edgeworth-Kuiper belt. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... Note: This article contains special characters. ...

The majority of objects (the so-called 'cold population'), have low inclinations and near circular orbits. A smaller population (the 'hot population') is characterised by highly inclined, more eccentric orbits^[1].

The recent Deep Ecliptic Survey reports the distributions of the two populations; one with the inclination centered at 4.6° (named Core) and another with inclinations extending beyond 30° (Halo). ^[2] The Deep Ecliptic Survey is a project to find Kuiper belt objects, using the facilities of the National Optical Astronomy Observatory. ...

Distribution

This diagram plots the distribution of all known cubewanos (532 as of February, 2006) and plutinos. Inserts on the right show histograms for orbit inclinations, eccentricity, and semi-major axes. Inserts on the left compare the populations of cubewanos and plutinos using eccentricity versus inclination plots.

The vast majority of KBOs (more than two-thirds) have inclinations of less than 5° and eccentricities of less than 0.1. Their semi-major axes show a preference for the middle of the main belt; arguably, smaller objects close to the limiting resonances have been either captured into resonance or have their orbits modified by Neptune. In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ... In statistics, a histogram is a graphical display of tabulated frequencies. ...

The 'hot' and 'cold' populations are strikingly different: more than 30% of all cubewanos are in low inclination, near-circular orbits. The parameters of the plutinos’ orbits are more evenly distributed, with a local maximum in moderate eccentricities in 0.15-0.2 range and low inclinations 5-10°. See also the comparison with scattered disk objects. The scattered disc (or scattered disk) is a distant region of our solar system, thinly populated by icy planetoids known as scattered disk objects (SDOs), a subset of the broader family of trans-Neptunian objects (TNOs). ...

This graph represents polar and ecliptic views of the (aligned) orbits of the classical objects - that is, cubewanos - in blue, together with the plutinos in red, and Neptune (yellow).

When the orbital eccentricities of cubewanos and plutinos are compared, it can be seen that the cubewanos form a clear 'belt' outside Neptune's orbit, whereas the plutinos approach, or even cross Neptune's orbits. When orbital inclinations are compared, 'hot' cubewanos can be easily distinguished by their higher inclinations, as the plutinos typically keep orbits below 20°. Image File history File links TheKuiperBelt_Projections_55AU_Classical_Plutinos. ... Image File history File links TheKuiperBelt_Projections_55AU_Classical_Plutinos. ...

Toward a formal definition

There is no official definition of 'cubewano' or 'classical KBO'. However, the terms are normally used to refer to objects free from significant perturbation from Neptune, thereby excluding KBOs in orbital resonance with Neptune (Resonant trans-Neptunian objects)). Furthermore, there is evidence that the Kuiper Belt has an 'edge', in that an apparent lack of low inclination objects beyond 47-49 AU was suspected as early as 1998 and shown with more data in 2001.^[3] Consequently, the traditional usage of the terms is based on the orbit’s semi-major axis, and includes objects situated between the 2:3 and 1:2 resonances, that is between 39.4 and 47.8 AU (with exclusion of these resonances and the minor ones in-between). ^[1] In astronomy, a resonant Trans-Neptunian Object is a Trans-Neptunian Object (TNO) in mean motion orbital resonance with Neptune. ... Look up Au, au in Wiktionary, the free dictionary. ...

However, these definitions lack precision: in particular the boundary between the classical objects and the scattered disk remains blurred. A recent classification by J. L. Elliott et al uses formal criteria based on the mean orbital parameters instead. Put informally, the definition includes the objects that have never crossed the orbit of Neptune. According to this definition, an object qualifies as a classical KBO if: The scattered disc (or scattered disk) is a distant region of our solar system, thinly populated by icy planetoids known as scattered disk objects (SDOs), a subset of the broader family of trans-Neptunian objects (TNOs). ...

• it is not resonant
• it has the average Tisserand's parameter exceeding 3
• its average eccentricity is less than 0.2.

Introduced by the report from the Deep Ecliptic Survey,^[2] this definition appears to be adopted in the most recent literature.^[4] In astronomy, a resonant Trans-Neptunian Object is a Trans-Neptunian Object (TNO) in mean motion orbital resonance with Neptune. ... In Celestial Mechanics, Tisserand’s parameter is a combination of orbital elements used in a restricted three-body problem. ...

External links

• David Jewitt's Kuiper Belt site @ University of Hawaii
• The Kuiper Belt Electronic Newsletter
• Minor Planet Center List of Trans-Neptunian objects
• TNO pages at johnstonarchive
• Plot of the current positions of bodies in the Outer Solar System

David C. Jewitt is a Professor of astronomy at the University of Hawaii Institute for Astronomy. ... This article is about the University of Hawaii system. ...

References

1. ^ ^{a b} D.Jewitt, A.Delsanti The Solar System Beyond The Planets in Solar System Update : Topical and Timely Reviews in Solar System Sciences , Springer-Praxis Ed., ISBN 3-540-26056-0 (2006). Preprint of the article (pdf)
2. ^ ^{a b} J. L. Elliot, S. D. Kern, K. B. Clancy, A. A. S. Gulbis, R. L. Millis, M. W. Buie, L. H. Wasserman, E. I. Chiang, A. B. Jordan, D. E. Trilling, and K. J. Meech The Deep Ecliptic Survey: A Search for Kuiper Belt Objects and Centaurs. II. Dynamical Classification, the Kuiper Belt Plane, and the Core Population. The Astronomical Journal, 129 (2006), pp. preprint
3. ^ Chadwick A. Trujillo and Michael E. Brown The Radial Distribution of the Kuiper Belt, The Astrophysical Journal, 554 (2001), pp. L95–L98 pdf
4. ^ E. Chiang, Y. Lithwick, M. Buie, W. Grundy, M. Holman A Brief History of Trans-Neptunian Space. to appear in Protostars and Planets V (August 2006) Final preprint on arXiv