Kuiper belt
The Kuiper Belt (English Kuiper belt ) is a ring-shaped, relatively flat region in our solar system beyond the orbit of Neptune extending in a distance of about 30 to 50 astronomical units (AU ) near the ecliptic and thousands of objects, including an estimated more than 70,000 objects with more than 100 km in diameter, contains.
Origin of the name
The name of the Kuiper Belt was coined by Scott Tremaine. Tremaine assessed and confirmed in 1988 with a computer simulation of a theory by Julio Ángel Fernández from its publication On the existence of a comet belt beyond Neptune in 1980 and named the still hypothetical region Kuiper belt based on Fernández ' publication, in the introduction was associated with a suspected comet belt and corresponding theories of Gerard Kuiper made between 1951 and 1974.
The term is controversial partly because Kuipers theory was neither the first of its kind, is still considered a date. Therefore, sometimes even from the Edgeworth Belt ( by Kenneth Edgeworth ) or Edgeworth - Kuiper Belt, the speech, since both Edgeworth (1949 in Ireland ) and Kuiper had (1951 in the U.S.) been suggested independently that a behind the orbit of Neptune area located in which of planetary material ( dust ) form comet.
The objects in this area are as Kuiper Belt Objects ( KBO ) and are among the trans-Neptunian objects ( TNO).
Classification
The known until now about 1000 objects in this region may be due to their orbital elements into several different groups:
- Resonant KBOs are objects that move in resonant orbits with Neptune and are thereby stabilized in its orbit at about 40 AU (for example Plutinos with a 3:2 resonance). One-third of the currently known KBOs are resonant KBOs.
- Classical KBOs ( CKBO or cubewanos ) move with small eccentricities on almost circular orbits 41-50 AE with orbital inclinations up to 30 °. The name derives from the Cubewano asteroid (15760) 1992 QB1 from (Q B One), which was discovered as the first of these objects. About two-thirds of the known KBOs move on such a circle-like orbit around the sun.
- Scattered KBOs ( SKBO or SDO ) move with large eccentricities on tracks with Periheldistanzen near 35 AE and AE Apheldistanzen to 1000. So far, only a few of these scattered KBOs known ( for example, ( 15874 ) 1996 TL66 with a highly elliptical orbit and an orbital inclination of 24 °).
Since 1978 it is known that Pluto with Charon has a very great companion, so one speaks also of the Pluto-Charon system. Between 1997 and 2001 a further eight dual systems were found among the known hitherto about 500 KBOs, spread across all three KBO groups.
Sub-regions of the Kuiper belt ( Distances in AE ):
The bars correspond to the scope of the mean orbital radii of the objects of the respective zones. The areas of the objects that are in orbital resonance with Neptune, in red. The orbit of Neptune and the Neptune Trojans are shown for reference only and not part of the Kuiper belt.
Formation
The KBOs are believed to have originated during the formation of planets near the region in which they are observed today. While very quickly formed many planetesimals in the denser inner region and very soon grew into planets, this process changed much more slowly in the thinner outer regions. The remnants form the observable today KBOs.
The CKBOs move nearly circular, as you would expect for this area resulting in objects. However, sometimes quite large orbital inclinations require a mechanism, which distracts from the ecliptic. This mechanism is not yet understood:
- One possibility is that Neptune has massive planetesimals scattered in the early stages of planet development ( larger than Earth ) in the Kuiper belt. These massive objects could explain the large orbital inclinations, but they would also have the resonant KBOs distracted more than it meets today's observations.
- A close of passing star caused the displacement from the ecliptic. This process would the resonant KBOs spare and also explain to the outer edge of the Kuiper Belt at 50 AU, but the star would need to approach the sun to a few hundred AU.
The SKBOs were probably scattered during the formation of the planetary system of the major planets outside. A portion was captured by Neptune on tracks near 35 AU perihelion, the rest were scattered further afield and even partially leave the solar system.
The formation processes of the dual systems have been pure speculation. The main problem of most proposals is the large number of these systems of large KBOs.
Comets
It is believed that much of the comet comes with average periods from the Kuiper belt. While in the past assumed that the comet nuclei are thrown off course KBOs almost unchanged, it is nowadays but believe that it is in the cometary nuclei to fragments derived from collisions of KBOs.
Large KBOs
As of 2005, eight KBOs are known, the diameter (with uncertainties of 10-15 %) to 1000 km or more. The largest known object in the Kuiper Belt are:
- Plutinos: Pluto ( 2390 km ) ( 90482 ) Orcus ( 1600-1800 km ), Charon (1270 miles), ( 28978 ) Ixion ( 400-550 km )
- CKBOs: ( 136472 ) Makemake (1800 miles), ( 136 108 ) Haumea (1300 × 1800 km ) (50000) Quaoar (1250 miles), (20000) Varuna ( 450-750 km )
- SKBOs: ( 136199 ) Eris ( 2326 km ), ( 55565 ) 2002 AW197 ( 890 km )
Discovery history
Extrasolar belt
Kuiper -like structures appear to have formed in other star systems. An example is Fomalhaut. There, a massive companion was found whose orbit extends inside the dust belt. Comparable planets are not expected in the solar system. Their existence would make it through a shift in the overall center of gravity relative to the Sun noticeable.
Zooniverse project IceHunters
Search within the framework of the Citizen Science project IceHunters volunteers in their spare time for objects in the Kuiper Belt to find a successor goal for the " New Horizons " spacecraft. To do this, values of images obtained from the subtraction of recorded at intervals astrononischen recordings. Astronomical knowledge is not necessary for this activity.