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| {{Use dmy dates|date=August 2011}}
| | Greetings! I am Marvella and I really feel comfortable when people use the full name. For a whilst I've been in South Dakota and my parents reside close by. For years he's been working as a meter reader and it's some thing he really appreciate. To collect cash is one of the issues I love most.<br><br>My webpage: [http://denisten.kr/xe/?mid=free&comment_srl=869&listStyle=webzine&document_srl=248250 home std test] |
| [[Image:InnerSolarSystem-en.png|300 px|thumb|[[Solar System#Inner Solar System|Inner Solar System]] diagram showing the Jupiter trojans (coloured green) in front of and behind [[Jupiter]] along its orbital path. Also shown is the asteroid belt (white) between the orbits of [[Mars]] and Jupiter and the [[Hilda family]] of asteroids (brown).]]
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| The '''Jupiter trojans''', commonly called '''Trojans''' or '''Trojan asteroids''', are a large group of objects that share the orbit of the planet [[Jupiter]] around the Sun. Relative to Jupiter, each trojan [[Libration|librates]] around one of Jupiter's two stable [[Lagrangian point]]s, ''{{L4}}'' and ''{{L5}}'', that respectively lie 60° ahead of and behind the planet in its orbit. Jupiter trojans are distributed in two elongated, curved regions around these Lagrangian points with an average [[semi-major axis]] of about 5.2 AU.<ref name=Yoshida2005/>
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| The first Jupiter trojan discovered, [[588 Achilles]], was spotted in 1906 by the German astronomer [[Max Wolf]].<ref name=Nicholson1961/> A total of 5,253 Jupiter trojans have been found {{as of|2012|March|lc=on}}.<ref name=count>{{cite web |title=Trojan Minor Planets |url=http://www.minorplanetcenter.org/iau/lists/Trojans.html |publisher=Minor Planet Center|accessdate=19 March 2012}}</ref> The term "trojan" derives from the fact that, by convention, they are each named after a mythological figure from the [[Trojan War]]. The total number of Jupiter trojans larger than 1 km in diameter is believed to be about {{Nowrap|1 million}}, approximately equal to the number of asteroids larger than 1 km in the [[asteroid belt]].<ref name=Yoshida2005/> Like main-belt asteroids, Jupiter trojans form [[Asteroid family|families]].<ref name=Jewitt2004/>
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| Jupiter trojans are dark bodies with reddish, featureless [[spectrum|spectra]]. No firm evidence of the presence of water, [[organic matter]] or other chemical compounds on their surfaces has been obtained. The Jupiter trojans' densities (as measured by studying [[Binary star|binaries]] or rotational lightcurves) vary from 0.8 to 2.5 g·cm<sup>−3</sup>.<ref name=Jewitt2004/> Jupiter trojans are thought to have been captured into their orbits during the early stages of the Solar System's formation or slightly later, during the [[planetary migration|migration]] of giant planets.<ref name=Jewitt2004/>
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| The term "[[Trojan (astronomy)|trojan]]" has come to be used more generally to refer to other [[Small Solar System body|small Solar System bodies]] with similar relationships to larger bodies: for example, there are both [[Mars trojan]]s and [[Neptune trojan]]s, and Saturn has [[trojan moon]]s.{{#tag:ref|Simulations suggest Saturn and Uranus have few if any trojans.<ref name="Nep">{{cite journal|last=Sheppard|first=SS |coauthors=CA Trujillo|date=28 July 2006|title=A thick cloud of Neptune trojans and their colors|journal=Science|location=New York|volume=313|issue=5786|pages=511–514 |oclc=110021198|url=http://www.ciw.edu/users/sheppard/pub/Sheppard06NepTroj.pdf|doi=10.1126/science.1127173|pmid=16778021|bibcode = 2006Sci...313..511S }}</ref>|group=Note}} NASA has announced the discovery of an [[2010 TK7|Earth trojan]].<ref>[http://www.nasa.gov/mission_pages/WISE/news/wise20110727.html NASA's WISE Mission Finds First Trojan Asteroid Sharing Earth's Orbit 27 July 2011]</ref><ref>{{Cite journal | last = Connors |first = Martin | coauthors = Paul Wiegert & Christian Veillet | title = Earth's Trojan asteroid | journal = Nature | volume = 475 | issue = 7357| pages = 481–483 | publisher = Nature | date = 28 July 2011 | url = | jstor = | doi = 10.1038/nature10233 |bibcode = 2011Natur.475..481C | pmid = 21796207 }}</ref> The term "Trojan asteroid" is normally understood to specifically mean the Jupiter trojans because the first trojans were discovered near Jupiter's orbit and Jupiter currently has by far the most known trojans.<ref name=count/>
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| == Observational history ==
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| [[File:Maximilian Franz Joseph Cornelius Wolf.jpg|thumb|right|upright|Maximilian Franz Joseph Cornelius Wolf (1890)—the discoverer of the first trojan]]
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| In 1772, Italian-born mathematician [[Joseph-Louis Lagrange]], in studying the [[restricted three-body problem]], predicted that a small body sharing an orbit with a planet but lying 60° ahead or behind it will be trapped near these points.<ref name=Nicholson1961/> The trapped body will [[libration|librate]] slowly around the point of equilibrium in a [[tadpole orbit|tadpole]] or [[horseshoe orbit]].<ref name=Marzari2002/> These leading and trailing points are called the {{L4}} and {{L5}} [[Lagrange point]]s.<ref name=Jewitt2000/>{{#tag:ref|The three other points—{{L1}}, {{L2}} and {{L3}}—are unstable.<ref name=Marzari2002/>|group=Note}} However, no asteroids trapped in Lagrange points were observed until more than a century after Lagrange's hypothesis. Those associated with Jupiter were the first to be discovered.<ref name=Nicholson1961/>
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| [[Edward Emerson Barnard|E. E. Barnard]] made the first recorded observation of a trojan, {{mpl|(12126) 1999 RM|11}}, in 1904, but neither he nor others appreciated its significance at the time.<ref name=Barnard1904>{{cite web |date=1 October 1999 |title=The Earliest Observation of a Trojan |publisher=Harvard-Smithsonian Center for Astrophysics (CfA) |author=Brian G. Marsden |url=http://www.cfa.harvard.edu/iau/pressinfo/TheFirstTrojanObs.html |accessdate=20 January 2009}}</ref> Barnard believed he saw the recently discovered [[Moons of Saturn|Saturnian satellite]] [[Phoebe (moon)|Phoebe]], which was only two [[arc-minute]]s away in the sky at the time, or possibly a [[star]]. The object's identity was not realized until its orbit was constructed in 1999.<ref name=Barnard1904/>
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| The first recognized discovery of a trojan occurred in February 1906, when astronomer [[Max Wolf]] of [[Heidelberg-Königstuhl State Observatory]] discovered an [[asteroid]] at the {{L4}} [[Lagrangian point]] of the [[Sun]]–[[Jupiter]] system, later named [[588 Achilles]].<ref name=Nicholson1961/> In 1906–1907 two more Jupiter trojans were found by fellow German astronomer [[August Kopff]] ([[624 Hektor]] and [[617 Patroclus]]).<ref name=Nicholson1961/> Hektor, like Achilles, belonged to the {{L4}} swarm ("ahead" of the planet in its orbit), whereas Patroclus was the first asteroid known to reside at the {{L5}} Lagrangian point ("behind" the planet).<ref name=Einarsson1913/> By 1938, 11 Jupiter trojans had been detected.<ref name=Wyse1938/> This number increased to 14 only in 1961.<ref name=Nicholson1961/> As instruments improved, the rate of discovery grew rapidly: by January 2000, a total of 257 had been discovered;<ref name=Jewitt2000/> by May 2003, the number had grown to 1,600.<ref name=Fernandes2003/> {{As of|2013|July}} there are 3,891 known Jupiter trojans at {{L4}} and 1,994 at {{L5}},<ref>{{cite web|title = List of Jupiter Trojans|accessdate =18 July 2013|url = http://www.minorplanetcenter.net/iau/lists/JupiterTrojans.html|publisher=Minor Planet Center}}</ref>
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| == Nomenclature ==
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| The custom of naming all asteroids in Jupiter's {{L4}} and {{L5}} points after famous heroes of the Trojan War was suggested by [[Johann Palisa]] of [[Vienna]], who was the first to accurately calculate their orbits.<ref name=Nicholson1961/> Asteroids in the {{L4}} group are named after [[Greece|Greek]] heroes (the "Greek node or camp" or "Achilles group"), and those at the {{L5}} point are named after the heroes of [[Troy]] (the "Trojan node or camp").<ref name=Nicholson1961/> Confusingly, 617 Patroclus was named before the Greece/Troy rule was devised, and a Greek name thus appears in the Trojan node; the Greek node also has one "misplaced" asteroid, 624 Hektor, named after a Trojan hero.<ref name=Wyse1938/>
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| == Numbers and mass ==
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| [[Image:Lagrange points.jpg|thumb|right|A [[gravitational potential]] contour plot showing Earth's Lagrangian points; {{L4}} and {{L5}} are above and below the planet, respectively. Jupiter's Lagrangian points are similarly situated in its much larger orbit.]]
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| Estimates of the total number of Jupiter trojans are based on deep surveys of limited areas of the sky.<ref name=Yoshida2005/> The {{L4}} swarm is believed to hold between 160–240,000 asteroids with diameters larger than 2 km and about 600,000 with diameters larger than 1 km.<ref name=Yoshida2005/><ref name=Jewitt2000/> If the {{L5}} swarm contains a comparable number of objects, there are more than {{Nowrap|1 million}} Jupiter trojans 1 km in size or larger. For the objects brighter than [[Absolute magnitude#Solar System bodies (H)|absolute magnitude]] 9.0 the population is probably complete.<ref name=Fernandes2003/> These numbers are similar to that of comparable asteroids in the asteroid belt.<ref name=Yoshida2005/> The total mass of the Jupiter trojans is estimated at 0.0001 of the mass of Earth or one-fifth of the mass of the asteroid belt.<ref name=Jewitt2000/>
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| Two more recent studies indicate, however, that the above numbers may overestimate the number of Jupiter trojans by several-fold. This overestimate is caused by (1) the assumption that all Jupiter trojans have a low albedo of about 0.04, whereas small bodies may actually have an average albedo as high as 0.12;<ref name=Fernandes2009/> (2) an incorrect assumption about the distribution of Jupiter trojans in the sky.<ref name=Nakamura2008/> According to the new estimates, the total number of Jupiter trojans with a diameter larger than 2 km is {{nowrap|6.3 ± 1.0{{e|4}}}} and {{nowrap|3.4 ± 0.5{{e|4}}}} in the {{L4}} and {{L5}} swarms, respectively.<ref name=Nakamura2008/> These numbers would be reduced by a factor of 2 if small Jupiter trojans are more reflective than large ones.<ref name=Fernandes2009/>
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| The number of Jupiter trojans observed in the {{L4}} swarm is slightly larger than that observed in {{L5}}. However, because the brightest Jupiter trojans show little variation in numbers between the two populations, this disparity is probably due to observational bias.<ref name=Jewitt2004/> However, some models indicate that the {{L4}} swarm may be slightly more stable than the {{L5}} swarm.<ref name=Marzari2002/>
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| The largest Jupiter trojan is [[624 Hektor]], which has an average diameter of 203 ± 3.6 km.<ref name=Fernandes2003/> There are few large Jupiter trojans in comparison to the overall population. With decreasing size, the number of Jupiter trojans grows very quickly down to 84 km, much more so than in the asteroid belt. A diameter of 84 km corresponds to an absolute magnitude of 9.5, assuming an [[albedo]] of 0.04. Within the 4.4–40 km range the Jupiter trojans' size distribution resembles that of the main-belt asteroids. An absence of data means that nothing is known about the masses of the smaller Jupiter trojans.<ref name=Marzari2002/> The size distribution suggests that the smaller Trojans are the products of collisions by larger Jupiter trojans.<ref name=Jewitt2004/>
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| == Orbits ==
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| [[Image:AnimatedOrbitOf624Hektor.gif|thumb|Animation of the orbit of 624 Hektor (blue), set against the orbit of Jupiter (outer red ellipse)]]
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| Jupiter trojans have orbits with radii between 5.05 and 5.35 AU (the mean semi-major axis is 5.2 ± 0.15 AU), and are distributed throughout elongated, curved regions around the two Lagrangian points;<ref name=Yoshida2005/> each swarm stretches for about 26° along the orbit of Jupiter, amounting to a total distance of about 2.5 AU.<ref name=Jewitt2000/> The width of the swarms approximately equals two [[Hill radius|Hill's radii]], which in the case of Jupiter amounts to about 0.6 AU.<ref name=Marzari2002/> Many of Jupiter trojans have large [[orbital inclination]]s relative to Jupiter's orbital plane—up to 40°.<ref name=Jewitt2000/>
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| Jupiter trojans do not maintain a fixed separation from Jupiter. They slowly librate around their respective equilibrium points, periodically moving closer to Jupiter or farther from it.<ref name=Marzari2002/> Jupiter trojans generally follow paths called [[tadpole orbit]]s around the Lagrangian points; the average period of their libration is about 150 years.<ref name=Jewitt2000/> The amplitude of the libration (along the Jovian orbit) varies from 0.6° to 88°, with the average being about 33°.<ref name=Marzari2002/> Simulations show that Jupiter trojans can follow even more complicated trajectories when moving from one Lagrangian point to another—these are called [[horseshoe orbit]]s (currently no Jupiter trojan with such an orbit is known).<ref name=Marzari2002/>
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| === Dynamical families and binaries ===
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| Discerning [[collisional family|dynamical families]] within the Jupiter-trojan population is more difficult than it is in the asteroid belt, because the Jupiter trojans are locked within a far narrower range of possible positions. This means that clusters tend to overlap and merge with the overall swarm. However, by 2003 roughly a dozen dynamical families were identified. Jupiter-trojan families are much smaller in size than families in the asteroid belt; the largest identified family, the Menelaus group, consists of only eight members.<ref name=Jewitt2004/>
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| In 2001, [[617 Patroclus]] was the first Jupiter trojan to be identified as a [[Minor-planet moon|binary asteroid]].<ref name="Merline">{{Cite web| last=Merline| first=W. J.| year=2001| url=http://cbat.eps.harvard.edu/iauc/07700/07741.html#Item2| title=IAUC 7741: 2001fc; S/2001 (617) 1; C/2001 T1, C/2001 T2}}</ref> The binary's orbit is extremely close, at 650 km, compared to 35,000 km for the primary's [[Hill sphere]].<ref name=Marchis2006/> The largest Jupiter trojan—[[624 Hektor]]—likely is a [[contact binary (asteroid)|contact binary]] with a moonlet.<ref name=Jewitt2004/><ref name=IAUC8732>{{cite web|url=http://cbat.eps.harvard.edu/iauc/08700/08732.html#Item1 |title=IAUC 8732: S/2006 (624) 1 |accessdate=23 July 2006}} (Satellite Discovery)</ref><ref name=Lacerda2007/>
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| == Physical properties ==
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| [[File:624Hektor-LB1-mag15.jpg|thumb|right|Trojan [[624 Hektor]] (at center) is similar in [[apparent magnitude|brightness]] to [[dwarf planet]] [[Pluto]].]]
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| Jupiter trojans are dark bodies of irregular shape. Their [[geometric albedo]]s generally vary between 3 and 10%.<ref name=Fernandes2003/> The average value is 0.056 ± 0.003 for the objects larger than 57 km,<ref name=Jewitt2004/> and 0.121 ± 0.003 (R-band) for those smaller than 25 km.<ref name=Fernandes2009/> The asteroid [[4709 Ennomos]] has the highest albedo (0.18) of all known Jupiter trojans.<ref name=Fernandes2003/> Little is known about the masses, chemical composition, rotation or other physical properties of the Jupiter trojans.<ref name=Jewitt2004/>
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| === Rotation ===
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| The rotational properties of Jupiter trojans are not well known. Analysis of the rotational [[light curve]]s of 72 Jupiter trojans gave an average rotational period of about 11.2 hours, whereas the average period of the control sample of asteroids in the asteroid belt was 10.6 hours.<ref name=Barucci2002/> The distribution of the rotational periods of Jupiter trojans appeared to be well approximated by a [[Maxwell distribution|Maxwellian function]],<ref group=Note>The Maxwellian function is <math>F=\begin{smallmatrix}\frac{1}{\sqrt{2\pi}\sigma}P^2\exp(-(P-P_0)^2/\sigma^2)\end{smallmatrix}</math>, where <math>P_0</math> is the average rotational period, <math>\sigma</math> is the [[Statistical dispersion|dispersion]] of periods.</ref> whereas the distribution for main-belt asteroids was found to be non-Maxwellian, with a deficit of periods in the range 8–10 hours.<ref name=Barucci2002/> The Maxwellian distribution of the rotational periods of Jupiter trojans may indicate that they have undergone a stronger collisional evolution compared to the asteroid belt.<ref name=Barucci2002/>
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| However, in 2008 a team from [[Calvin College]] analyzed the [[light curve]]s of a debiased sample of ten Jupiter trojans, and found a [[median]] spin period of 18.9 hours. This value was significantly higher than that for main-belt asteroids of similar size (11.5 hours). The difference could mean that the Jupiter trojans possess a lower average density, which may imply that they formed in the [[Kuiper belt]] (see below).<ref>{{cite journal|last=Molnar| first=Lawrence A.|coauthors=Melissa J. Haegert, and Kathleen M. Hoogeboom|date=April 2008|title=Lightcurve Analysis of an Unbiased Sample of Trojan Asteroids|journal=The Minor Planet Bulletin|publisher=Association of Lunar and Planetary Observers|volume=35|pages=82–84|oclc=85447686|bibcode=2008MPBu...35...82M|last2=Haegert|last3=Hoogeboom}}</ref>
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| === Composition ===
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| [[Spectroscopy|Spectroscopically]], the Jupiter trojans mostly are [[D-type asteroid]]s, which predominate in the outer regions of the asteroid belt.<ref name=Jewitt2004/> A small number are classified as [[P-type asteroid|P]] or [[C-type asteroid]]s.<ref name=Barucci2002/> Their spectra are red (meaning that they reflect more light at longer wavelengths) or neutral and featureless.<ref name=Fernandes2003/> No firm evidence of water, organics or other chemical compounds has been obtained {{as of|2007|lc=on}}. However, [[4709 Ennomos]] has an albedo slightly higher than the Jupiter-trojan average, which may indicate the presence of water ice. In addition, a number of other Jupiter trojans, such as [[911 Agamemnon]] and [[617 Patroclus]], have shown very weak absorptions at 1.7 and 2.3 μm, which might indicate the presence of organics.<ref>{{cite journal|title=Spectroscopic Search for Water Ice on Jovian Trojan Asteroids|author=Yang, Bin and Jewitt, David|year=2007|journal=The Astronomical Journal|volume= 134|issue=1|pages=223–228|doi=10.1086/518368|url=http://www.iop.org/EJ/abstract/1538-3881/134/1/223/|accessdate=19 January 2009|bibcode=2007AJ....134..223Y}}</ref> The Jupiter trojans' spectra are similar to those of the [[Moons of Jupiter#Irregular satellites|irregular moons of Jupiter]] and, to certain extent, [[comet nuclei]], though Jupiter trojans are spectrally very different from the redder [[Kuiper belt object]]s.<ref name=Yoshida2005/><ref name=Jewitt2004/> A Jupiter trojan's spectrum can be matched to a mixture of water ice, a large amount of carbon-rich material ([[charcoal]]),<ref name=Jewitt2004/> and possibly [[magnesium]]-rich [[silicate]]s.<ref name=Barucci2002/> The composition of the Jupiter trojan population appears to be markedly uniform, with little or no differentiation between the two swarms.<ref>{{cite journal|title=The surface composition of Jupiter Trojans: Visible and near-infrared survey of dynamical families|author=Dotto, E., Fornasier, S., Barucci, M.A., et al.|journal=Icarus|volume=183|issue=2|date= August 2006|pages= 420–434|doi=10.1016/j.icarus.2006.02.012|url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WGF-4JT38N8-3&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b23513f67484eaff2979db06148e99a5|accessdate=17 January 2009|bibcode=2006Icar..183..420D}}</ref>
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| A team from the [[Keck Observatory]] in Hawaii announced in 2006 that it had measured the density of the binary Jupiter trojan [[617 Patroclus]] as being less than that of water ice (0.8 g/cm<sup>3</sup>), suggesting that the pair, and possibly many other Trojan objects, more closely resemble [[comet]]s or [[Kuiper belt]] objects in composition—water ice with a layer of dust—than they do the main-belt asteroids.<ref name=Marchis2006/> Countering this argument, the density of Hektor as determined from its rotational lightcurve (2.480 g/cm<sup>3</sup>) is significantly higher than that of 617 Patroclus.<ref name=Lacerda2007/> Such a difference in densities is puzzling and indicates that density may not be a good indicator of asteroid origin.<ref name=Lacerda2007/>
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| == Origin and evolution ==
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| Two main theories have emerged to explain the formation and evolution of the Jupiter trojans. The first suggests that the Jupiter trojans formed in the same part of the [[Solar System]] as Jupiter and entered their orbits while it was forming.<ref name=Marzari2002/> The last stage of Jupiter's formation involved runaway growth of its mass through the accretion of large amounts of [[hydrogen]] and [[helium]] from the [[protoplanetary disk]]; during this growth, which lasted for only about 10,000 years, the mass of Jupiter increased by a factor of ten. The [[planetesimal]]s that had approximately the same orbits as Jupiter were caught by the increased gravity of the planet.<ref name=Marzari2002/> The capture mechanism was very efficient—about 50% of all remaining planetesimals were trapped. This hypothesis has two major problems: the number of trapped bodies exceeds the observed population of Jupiter trojans by four [[order of magnitude|orders of magnitude]], and the present Jupiter trojan asteroids have larger orbital inclinations than are predicted by the capture model.<ref name=Marzari2002/> However, simulations of this scenario show that such a mode of formation also would inhibit the creation of similar trojans for [[Saturn]], and this has been borne out by observation: to date no trojans have been found near Saturn.<ref>{{cite journal|title=The growth of Jupiter and Saturn and the capture of Trojans|last=Marzari|first=F.|journal=Astronomy and Astrophysics|volume=339|pages=278–285|year=1998|bibcode=1998A&A...339..278M|last2=Scholl|first2=H.}}</ref>
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| The second theory, part of the [[Nice model]], proposes that the Jupiter trojans were captured during [[planetary migration]], which happened about {{Nowrap|500–600 million}} years after the Solar System's formation.<ref name=Levison2007/> The migration was triggered by the passage of Jupiter and Saturn through the 1:2 mean motion [[orbital resonance|resonance]]. During this period [[Uranus]], [[Neptune]] and to some extent Saturn moved outward, whereas Jupiter moved slightly inward.<ref name=Levison2007/> Migrating giant planets destabilized the primordial [[Kuiper belt]], throwing millions of objects into the inner Solar System. In addition, their combined gravitational influence would have quickly disturbed any pre-existing Jupiter trojans.<ref name=Levison2007/> In this theory, the present Jupiter-trojan population eventually accumulated from runaway Kuiper belt objects as Jupiter and Saturn moved away from the resonance.<ref name="Morbidelli">{{cite journal|last=Morbidelli|first=A.|coauthors=Levison, HF; Tsiganis, K; Gomes, R|date=26 May 2005|title=Chaotic capture of Jupiter's Trojan asteroids in the early Solar System|journal=Nature|volume=435|issue=7041|pages=462–465 |oclc=112222497|url=http://www.oca.eu/michel/PubliGroupe/MorbyNature2005.pdf|doi=10.1038/nature03540|pmid=15917801|bibcode = 2005Natur.435..462M }}</ref>
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| The long-term future of the Jupiter trojans is open to question, because multiple weak resonances with Jupiter and Saturn cause them to behave chaotically over time.<ref name=Robutal2005/> In addition, collisional shattering slowly depletes the Jupiter-trojan population as fragments are ejected. Ejected Jupiter trojans could become temporary satellites of Jupiter or [[Jupiter-family comet]]s.<ref name=Jewitt2004/> Simulations show that the orbits of up to 17% of Jupiter trojans are unstable over the age of the Solar System.<ref>{{cite journal|title=Chaotic Diffusion And Effective Stability of Jupiter Trojans |author=Kleomenis Tsiganis, Harry Varvoglis and Rudolf Dvorak|year=2004|publisher=Springer|journal=Celestial Mechanics and Dynamical Astronomy|volume=92|date=April 2005|doi=10.1007/s10569-004-3975-7|pages=71–87|url=http://www.springerlink.com/content/vp38717557064k15/|accessdate=17 January 2009|issue=1–3|bibcode = 2005CeMDA..92...71T }}</ref> Levison et al. believe that roughly 200 ejected Jupiter trojans greater than 1 km in diameter might be traveling the Solar System, with a few possibly on Earth-crossing orbits.<ref name=Levison1997>{{cite journal|title=Dynamical evolution of Jupiter's Trojan asteroids|author=Levison, Harold F.; Shoemaker, Eugene M.; Shoemaker, Carolyn S.|journal=Nature|volume=385|issue=6611|pages=42–44|year=1997|doi=10.1038/385042a0|url=http://www.nature.com/nature/journal/v385/n6611/abs/385042a0.html|accessdate=19 January 2009|bibcode = 1997Natur.385...42L }}</ref> Some of the escaped Jupiter trojans may become Jupiter-family comets as they approach the Sun and their surface ice begins evaporating.<ref name=Levison1997/>
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| == See also ==
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| {{colbegin}}
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| * [[List of Jupiter trojans (Greek camp)]]
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| * [[List of Jupiter trojans (Trojan camp)]]
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| * [[Pronunciation of Jupiter trojans' names]]
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| * [[List of objects at Lagrangian points]]
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| * [[List of Jupiter-crossing minor planets]]
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| * [[Comet Shoemaker–Levy 9]]
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| {{colend}}
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| == Notes ==
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| <references group=Note/>
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| == References ==
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| {{reflist|colwidth=30em|refs=
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| <ref name="Jewitt2000">{{cite journal|last=Jewitt|first=David C.|coauthors=Trujillo, Chadwick A.; Luu, Jane X.|title=Population and size distribution of small Jovian Trojan asteroids|year=2000|journal=The Astronomical journal|volume=120|issue=2|pages=1140–7|doi=10.1086/301453|bibcode=2000AJ....120.1140J|arxiv = astro-ph/0004117 }}</ref>
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| <ref name="Yoshida2005">{{cite journal|last=Yoshida|first=F.|coauthors=Nakamura, T|title=Size distribution of faint {{L4}} Trojan asteroids|year=2005|journal=The Astronomical journal|volume=130|issue=6|pages=2900–11|doi=10.1086/497571|bibcode=2005AJ....130.2900Y}}</ref>
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| <ref name="Wyse1938">{{cite journal|last=Wyse|first=A.B.|title=The Trojan group|year=1938|journal=Astronomical Society of the Pacific Leaflets|volume=3|pages=113–19|bibcode=1938ASPL....3..113W}}</ref>
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| <ref name="Einarsson1913">{{cite journal|last=Einarsson|first=Sturla|title=The Minor Planets of the Trojan Group|year=1913|journal=Publications of the Astronomical Society of the Pacific|volume=25|pages=131–3|bibcode=1913PASP...25..131E|doi=10.1086/122216}}</ref>
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| <ref name=Nakamura2008>{{cite journal|last=Nakamura|first=Tsuko|coauthors=Yoshida, Fumi|title=A New Surface Density Model of Jovian Trojans around Triangular Libration Points|year=2008|journal=Publications of the Astronomical Society of Japan|volume=60|pages=293–296|bibcode=2008PASJ...60..293N|last2=Yoshida}}</ref>
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| <ref name="Nicholson1961">{{cite journal|last=Nicholson|first=Seth B.|title=The Trojan asteroids|year=1961|journal=Astronomical Society of the Pacific Leaflets|volume=8|pages=239–46|bibcode=1961ASPL....8..239N}}</ref>
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| <ref name="Marzari2002">{{cite book|last=Marzari|first=F.|coauthors=Scholl, H.; Murray C.; Lagerkvist C.|year=2002 |chapter=Origin and Evolution of Trojan Asteroids|title=Asteroids III|publisher=University of Arizona Press|pages=725–38|location=Tucson, Arizona| url=http://www.lpi.usra.edu/books/AsteroidsIII/pdf/3007.pdf|format=PDF}}</ref>
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| <ref name="Barucci2002">{{cite book|last=Barucci|first=M.A.|coauthors=Kruikshank, D.P.; Mottola S.; Lazzarin M.|year=2002 |chapter=Physical Properties of Trojan and Centaur Asteroids|title=Asteroids III|publisher=University of Arizona Press|pages=273–87|location=Tucson, Arizona}}</ref>
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| <ref name="Levison2007">{{cite journal | author=Harold F. Levison, Alessandro Morbidelli, Crista Van Laerhoven et al. | title=Origin of the Structure of the Kuiper Belt during a Dynamical Instability in the Orbits of Uranus and Neptune|year=2007| bibcode=2008Icar..196..258L | arxiv=0712.0553 | doi=10.1016/j.icarus.2007.11.035 | journal=Icarus | volume=196 | issue=1 | page=258 }}</ref>
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| <ref name="Marchis2006">{{cite journal|last=Marchis|first=Franck|coauthors=Hestroffer, Daniel; Descamps, Pascal ''et al.''|title=A low density of 0.8 g cm<sup>−3</sup> for the Trojan binary asteroid 617 Patroclus|year=2006|journal=Nature|volume=439|issue=7076|pages=565–567|bibcode=2006Natur.439..565M|doi=10.1038/nature04350|pmid=16452974|arxiv = astro-ph/0602033 }}</ref>
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| <ref name="Fernandes2003">{{cite journal|last=Fernandes|first=Yanga R.|coauthors=Sheppard, Scott S.; Jewitt, David C.|title=The albedo distribution of Jovian Trojan asteroids|year=2003|journal=The Astronomical Journal|volume=126|issue=3|pages=1563–1574|bibcode=2003AJ....126.1563F|doi=10.1086/377015}}</ref>
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| <ref name=Fernandes2009>{{cite doi|10.1088/0004-6256/138/1/240}}</ref>
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| <ref name="Lacerda2007">{{cite journal|last=Lacerda|first=Pedro|coauthors=Jewitt, David C.|title=Densities of Solar System Objects from Their Rotational Light Curves|year=2007|journal=The Astronomical journal|volume=133|issue=4|pages=1393–1408|doi=10.1086/511772|bibcode=2007AJ....133.1393L|arxiv = astro-ph/0612237 }}</ref>
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| <ref name="Jewitt2004">{{cite book|last=Jewitt|first=David C.|coauthors=Sheppard, Scott, and Porco, Carolyn|chapter=Jupiter’s Outer Satellites and Trojans|title=Jupiter: The planet, Satellites and Magnetosphere|year=2004|publisher=Cambridge University Press|editor=Bagenal, F.; Dowling, T.E.; McKinnon, W.B.| url=http://www.dtm.ciw.edu/users/sheppard/pub/Sheppard04JupChapter.pdf|format=pdf}}</ref>
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| <ref name="Robutal2005">{{cite journal|last=Robutal|first=P.|coauthors=Gabern, F.; Jorba A.|title=The observed Trojans and the global dynamics around the lagrangian points of the sun–jupiter system|year=2005|journal=Celestial Mechanics and Dynamical Astronomy|volume=92|issue=1–3|pages=53–69|doi=10.1007/s10569-004-5976-y|url=http://www.cds.caltech.edu/~gabern/preprints/osterreich.pdf|format=PDF|bibcode = 2005CeMDA..92...53R }}</ref>
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| }}
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| == External links ==
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| {{Commons category|Jupiter Trojans}}
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| * {{cite web|url=http://www.minorplanetcenter.org/iau/lists/Trojans.html|title=Minor Planet Center's List of Trojan Minor Planets}}
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| * {{cite web|last=Sheppard|first=Scott|url=http://www.dtm.ciw.edu/users/sheppard/satellites/trojan.html|title=The Trojan Page}}
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| * {{cite journal|last=Lykawka|coauthors=Horner|title=The Capture of Trojan Asteroids by the Giant Planets During Planetary Migration|first1=P. S.|doi=10.1111/j.1365-2966.2010.16538.x|year=2010|journal=Monthly Notices of the Royal Astronomical Society|volume=405|issue=1383|arxiv=1003.2137|bibcode=2010MNRAS.405.1375L}}
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| * [http://www.jpl.nasa.gov/news/news.php?release=2012-322 NASA's WISE Colors in Unknowns on Jupiter Asteroids] (NASA 2012-322 : October 15, 2012)
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| {{Asteroids}}
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| {{Jupiter}}
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| {{Small Solar System bodies}}
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| {{featured article}}
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| [[Category:Jupiter trojans| ]]
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| {{Link FA|es}}
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| {{Link GA|it}}
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