Cubewano

Encyclopedia : C : CU : CUB : Cubewano

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TNOs and similar bodies
cis-Neptunian objects * centaurs * Neptune Trojans trans-Neptunian objects (TNOs) * Kuiper belt objects (KBOs) ** cubewanos (classical KBOs) ** plutinos (2:3 resonant KBOs) ** twotinos (1:2 resonant KBOs) * scattered disc objects (SDOs) * Oort cloud objects (OCOs)

A cubewano is a Kuiper belt object, orbiting beyond Pluto and not controlled by resonances with Neptune. Cubewanos, also called Classical Kuiper Belt objects, have semi-major axes in 40-50 AU range and, unlike Pluto, do not cross Neptune’s orbit.

The odd name is derived from the first trans-Neptunian object found, (15760) 1992 QB₁. Later objects were called "QB1-o's", or cubewanos.

Objects identified as cubewanos include:

• (15760) 1992 QB₁
• 2005 FY₉ the largest known cubewano and one of the largest trans-Neptunian objects
• 2003 EL₆₁, notable for its two moons and rapid rotation (3.9h)
• (50000) Quaoar
• (20000) Varuna
• (19521) Chaos
• (53311) Deucalion

Orbits

Most classical Kuiper objects are found between the 2:3 orbital resonance with Neptune (populated by plutinos) and the 1:2 resonance. The diagram illustrates larger cubewanos with semi-major axis on X axis. The eccentricity of the orbits is represented by red segments (extending from perihelion to aphelion) with inclination represented on Y axis.

The largest plutinos (Pluto, 90482 Orcus and 28978 Ixion) are also plotted for comparison (in grey). 50000 Quaoar, for example, has a typical, near circular (short red segment), close to the ecliptic orbit. Plutinos on the other hand, have more eccentric orbits bringing some of them closer to the Sun than Neptune (marked as 1:1 resonance).

The majority of objects, so called cold population, have low inclination, near circular orbits. (the brightest: 1997 CS₂₉, 2001 QT₂₉₇ and 2001 QS₃₂₂ are shown on the diagram). A smaller population, named hot, is characterised by highly inclined, more eccentric orbitsD.Jewitt,A.Delsanti The Solar System Beyond The Planets,to appear in the book Solar System Update, Springer-Praxis Ed., Horwood, Blondel and Mason, 2006. [Preprint version (pdf)].

Distribution

The distribution of all known cubewanos (532 as of February, 2006) is plotted on the second diagram. The small inserts on the right show histograms for orbit inclinations i (5° interval) and eccentricity e (interval 0.05).¹ The vast majority of objects (more than ²/₃) have inclination < 5° and eccentricity <0.1. The distribution of semi-major axis a, also shown, illustrates the 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.

The inserts on the left side of the diagram compare the populations of cubewanos and plutinos Minor Planet Circular 2005-X77 [Distant Minor planets] was used for plutinos' orbits classification. The updated data can be found in [MPC 2006-D28]. using eccentricity versus inclination plots. Each small square represents a given range for both the eccentricity e and the inclination i ². The relative population of objects within this range is represented with ‘cartographic’ colours (from small numbers plotted as green valleys to brown peaks³.

The two populations are quite different: more than 30% of all cubewanos are on low inclination, near circular orbits (the low bottom corner ‘peak’). The parameters of 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.

¹Distribution of plutinos is plotted but excluded from cubewanos’ histograms. ²As near-circular orbits occupy the first column (e<0.05) and the orbits with the lowest inclination (i<5 degrees) occupy the lowest row, the square in the bottom left corner represents the number of near circular, very lowly inclined orbits. ³A grey square represents a single object (an outlier) in this range.

Orbit plots

The graph on the left represents polar and ecliptic views of the (aligned) orbits of the classical objects (in blue) together with the plutinos (in red)¹.

The solid blue ring, resulting from hundreds of overlapping orbits of the classical objects, fully deserves the name of the main (classical or cubewanos) belt. Unlike the classical objects with the orbits entirely outside, the plutinos approach, or even cross, the orbit of Neptune (in yellow).

On the ecliptic view, the yellow arc represents Neptune’s orbit (at ~30AU). The perihelion, typically inside Neptune’s orbit for the plutinos, and always safely outside for the cubewanos, is the distinctive attribute between the two families. Hot cubewanos can also be easily distinguished by their inclination, the plutinos typically keeping orbits below 20°.

^{1For roughly a half of known TNO the orbits are not yet known with the precision sufficient for the classification (a particularly delicate task for resonant objects).}

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]

References

The minor planets
Vulcanoids | Near-Earth asteroids | Main belt | Jupiter Trojans | Centaurs | Damocloids | Comets | Trans-Neptunians (Kuiper belt · Scattered disc · Oort cloud)
For other objects and regions, see: , , asteroid moons and the Solar system For a complete listing, see: List of asteroids. See also Pronunciation of asteroid names and Meanings of asteroid names.

Trans Neptunian Objects [[http://encycl.opentopia.com/ edit ]]

Planet : Pluto | 2003 UB313 Plutino : Pluto* | 1993 RO | 1993 RP | | 1993 SC | 1994 TB | 1995 QZ9 | 1996 SZ4 | 1996 TP66 | 38083 Rhadamanthus | 38628 Huya | 28978 Ixion | 2003 VS2 | 90482 Orcus Cubewanos: 1992 QB1 | 1994 GV9 | 1994 JQ1 | 1994 VK8 | 1996 TO66 | 19521 Chaos | 53311 Deucalion | 2002 AW197 | 50000 Quaoar | 2002 MS4 | 2002 TX300 | 2002 UX25 | 1997 CQ29 = 58534 Logos | 2003 AZ84 | 2003 EL61 | 2003 QW90 | 2005 FY9 Twotino: 1996 TR66 | 1998 SM165 | 1997 SZ10 | 1999 RB216 | 2000 JG81 Scattered disk object: 1995 TL8 | 1996 GQ21 | 1996 TL66 | 2000 OO67 | 2000 OM67 | 2001 KC77 | 2001 UR163 | 2002 CY224 | 2002 GX32 | 2003 UB313** Unclassified Objects : 1994 JS | 1994 JR1 | 1995 DA2 | 1995 SM55 | 1996 TQ66 | 1997 CR29 | 1997 CS29 | 1997 CU29 | 1997 QJ4 | 1998 HJ151 | 1998 HK151 | 1998 HP151 | 1998 HM151 | 1998 KR65 | 1998 SM165 | 1998 SN1651998 US43 | 1998 VG44 | 1998 WW24 | 1998 WA31 | 1998 WU31 | 1998 WW31 | 1998 WA25 | 1999 CP133 | 1999 CL158 | 1999 CC158 | 1999 DF9 | 1999 HT11 | 1999 HB12 | 1999 HC12 | 1999 KR16 | 1999 OY3 Natural satellites : Charon (Pluto) | Hydra (Pluto) | Nix (Pluto) | S/2000 (1998 WW31) 1 | S/2005 (2003 EL61) 1 | S/2005 (2003 EL61) 2 | S/2005 (2003 UB313) 1 |}   From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating. All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details. Search Titles 0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z ? E-mail this article to: Personal Message: