50000 Quaoar 100579 226184611 2008-07-17T05:54:27Z Eric Kvaalen 122969 Explanation for round "minor planet number", taken from French Wikipedia. {{redirect|Quaoar|the Tongva god|Quaoar (mythology)}} <!-- Additional parameters for this template are available at [[Template:Infobox Planet]]. --> {{Infobox Planet | minorplanet = yes | discovery=yes | discovery_ref = <ref>[http://cfa-www.harvard.edu/iau/lists/NumberedMPs.html Discovery Circumstances: Numbered Minor Planets<!-- Bot generated title -->]</ref> | physical_characteristics = yes | bgcolour=#FFFFC0 | name=50000 Quaoar | image= [[Image:Quaoar_PRC2002-17e.jpg|250px]] | caption= Sum of 16 Hubble exposures registered on Quaoar. | discoverer=[[Chad Trujillo]],<br>[[Michael E. Brown]] | discovered=[[June 4]], [[2002]] | alt_names=2002 LM<sub>60</sub> <ref>[http://cfa-www.harvard.edu/iau/MPDes.html Minor Planet Designations<!-- Bot generated title -->]</ref> | mp_category=[[Kuiper belt]] | orbit_ref = <ref>[http://asteroid.lowell.edu Asteroid Data Services by Lowell Observatory<!-- Bot generated title -->]</ref> | epoch=[[May 18]], [[2008]] ([[Julian day|JD]] 2454600.5) | semimajor=6.493296 [[Tera|T]][[metre|m]] (43.607 [[Astronomical unit|AU]]) | perihelion=6.270316 Tm (41.928 AU) | aphelion=6.716275 Tm (45.286 AU) | eccentricity=0.0384 | period=105181.6 [[day|d]] (287.97 [[Julian year (astronomy)|a]]) | inclination=7.988[[degree (angle)|°]] | asc_node=188.893° | arg_peri=148.508° | mean_anomaly=284.861° | avg_speed=4.52 km/[[second|s]] | dimensions= 1,260 ± 190 km (direct)<ref name="Brown2004">{{cite journal | author=[[Michael E. Brown]] and [[Chadwick A. Trujillo]] | title=''Direct Measurement of the Size of the Large Kuiper Belt Object (50000) Quaoar''| journal=The Astronomical Journal | volume=127 | issue=7018 | year=2004 | pages=2413–2417 | doi=10.1086/382513}} [http://www.gps.caltech.edu/~mbrown/papers/ps/qu.pdf Reprint ] on Brown's site (pdf)</ref> <br/>844{{±|207|190}} km (thermal)<ref name="StansberryGrundy">Stansberry J., Grundy W., Brown M, Cruikshank D., Spencer J., Trilling D., Margot J-L ''Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope'' To Appear in: Kuiper Belt (M.A. Barucci et al., Eds.) U. Arizona Press, 2007 [http://www.arxiv.org/abs/astro-ph/0702538 Preprint]</ref> | mass=1.0-2.6×10<sup>21</sup> [[kilogram|kg]] | density=2.0? g/[[cubic centimetre|cm³]] | surface_grav=0.276-0.376 m/s² | escape_velocity=0.523-0.712 km/s | spectral_type=(moderately red) B-V=0.94, V-R=0.65 | abs_magnitude=2.6 | albedo=0.088 {{±|0.021|0.012}} <ref name="Brown2004"/> <br/>0.1986 {{±|0.13|0.07}} <ref name="StansberryGrundy"/> | single_temperature=~43 [[kelvin|K]] }} '''50000 Quaoar''' ({{pronEng|ˈkwɑːwɑr}} or {{IPA|/ˈkwaʊɚ/}} (''kwaa'·waar'' or ''kwow'·ər''), [[Tongva language|Tongva]] {{IPA|[qʷɑoɑr]}}, [http://www.gps.caltech.edu/~chad/quaoar]) is a [[Trans-Neptunian object]] orbiting the Sun in the [[Kuiper belt]]. It was discovered on [[June 4]], [[2002]] by astronomers [[Chad Trujillo]] and [[Michael E. Brown|Michael Brown]] at the [[California Institute of Technology]] from images acquired at the [[Samuel Oschin Telescope]] at [[Palomar Observatory]]. == Discovery == The discovery of Quaoar, a [[apparent magnitude|magnitude]] 18.5 object located in the [[constellation]] [[Ophiuchus]], was announced on [[October 7]], [[2002]], at a meeting of the [[American Astronomical Society]]. The earliest [[precovery|prediscovery image]] proved to be a [[May 25]], [[1954]] plate from Palomar Observatory. It may qualify as a [[dwarf planet]], given its size inferred from direct observation by the [[Hubble Space Telescope]]. == Name == The planetoid's name follows [[International Astronomical Union]] rules by naming [[trans-Neptunian objects]] after [[Deity|deities]] associated with [[creation myth]]s (see [[planetary nomenclature]]). “[[Quaoar (deity)|Quaoar]]” is the name of a creation deity of the [[Native Americans in the United States|Native American]] [[Tongva]] people, native to the area around [[Los Angeles, California|Los Angeles]], where the discovery was made. The IAU approved the name Quaoar, making it the official name; it also has the [[provisional designation]] '''{{mp|2002 LM|60}}'''. The “memorable” [[minor planet number]] 50000 is not a coincidence but is a witness to the exciting race to discover a Pluto-sized object. The [[Minor Planet Center]] normally gives a sequential number to an object once its orbit has been well determined, but the numbering is done by block, so they can cheat a little to give a round number to an exceptional object.<!--Explanation taken from French Wikipedia.--> Quaoar’s discovery followed that of {{dp|Varuna|20000 Varuna}} and was in turn followed by bigger discoveries (see [[#Size|below]]). The efforts were finally rewarded with the discovery of an object bigger than Pluto, namely {{dp|Eris}}. == Size == <!--- [[Image:EightTNOs.png|thumb|250px|left|Quaoar compared to {{dp|Eris}}, [[Pluto]], {{dp|Makemake}}, {{mpl-|136108|2003 EL|61}}, {{dp|Sedna}}, {{dp|Orcus}}, {{dp|Varuna}}, and [[Earth]].]] ---> <imagemap> Image:EightTNOs.png|thumb|250px|left|Quaoar compared to Eris, Pluto, Makemake, (136108) 2003 EL<sub>61</sub>, Sedna, Orcus, Varuna, and Earth. #Earth rect 646 1714 2142 1994 [[Earth|The Earth]] #Eris and Dysnomia circle 226 412 16 [[Dysnomia (moon)|Dysnomia]] circle 350 626 197 [[Eris (dwarf planet)|(136199) Eris]] #Pluto and Charon circle 1252 684 86 [[Charon (moon)|Charon]] circle 1038 632 188 [[Pluto|(134340) Pluto]] #Makemake circle 1786 614 142 [[Makemake (dwarf planet)|(136472) Makemake]] #2003 EL61 circle 2438 616 155 [[(136108) 2003 EL61]] #Sedna circle 342 1305 137 [[90377 Sedna|(90377) Sedna]] #Orcus circle 1088 1305 114 [[90482 Orcus|(90482) Orcus]] #Quaoar circle 1784 1305 97 [[50000 Quaoar|(50000) Quaoar]] #Varuna circle 2420 1305 58 [[20000 Varuna|(20000) Varuna]] desc none # - setting this to "bottom-right" will display a (rather large) icon linking to the graphic, if desired #Notes: #Details on the new coding for clickable images is here: [[mw:Extension:ImageMap]] #While it may look strange, it's important to keep the codes for a particular system in order. The clickable coding treats the first object created in an area as the one on top. #Moons should be placed on "top" so that their smaller circles won't disappear "under" their respective primaries. </imagemap> Quaoar is estimated to have a diameter of 1,260 ± 190 km<ref name="Brown2004"/>, which at the time of discovery in 2002 made it the largest object found in the [[solar system]] since the discovery of [[Pluto]]. Quaoar was later supplanted by {{dp|Eris}}, {{dp|Sedna}}, {{mpl-|136108|2003 EL|61}}, and {{dp|Makemake}}. In addition, it is likely that the subsequently discovered [[plutino]] {{dp|Orcus}} is also larger than Quaoar. Quaoar's volume is somewhat more than all of the [[asteroid]]s put together. It is roughly one tenth the diameter of [[Earth]], one third the diameter of the [[Moon]] or half the size of [[Pluto]]. Quaoar was the first [[trans-Neptunian object]] to be measured ''directly'' from [[Hubble Space Telescope]] (HST) images, using a new, sophisticated method (see [http://www.gps.caltech.edu/~mbrown Brown’s pages] for a non-technical description and his paper<ref name="Brown2004"/> for details). Given its distance Quaoar is on the limit of the HST resolution (40 [[milliarcsecond]]s) and its image is consequently "smeared" on a few adjacent pixels. By comparing carefully this image with the images of stars in the background and using a sophisticated model of HST optics ([[point spread function]] (PSF)), Brown and Trujillo were able to find the best fit disk size which would give a similar blurred image. This method was recently applied by the same authors to measure the size of {{dp|Eris}}. However, these estimates only marginally agree with the recent (2007) [[infrared]] measurements by [[Spitzer Space Telescope]] suggesting a much larger [[albedo]] (0.19) and consequently a smaller diameter (844.4 {{±|206.7|189.6}} km)<ref name="StansberryGrundy"/>. <br clear=left/> == Orbit == [[Image:TheKuiperBelt_Orbits_Quaoar.svg|left|thumb|250px|Orbits of Quaoar and Pluto - ecliptic view.]] [[Image:TheKuiperBelt_Orbits_Quaoar_PolarView.svg|left|thumb|250px|Orbits of Quaoar (blue) and Pluto (red) - polar view.]] Quaoar orbits at about [[1 E+12 m|6]] billion kilometres (3.7 billion miles) from the [[Sun]] with an orbital period of [[1 E9 s|287 years]]. The orbit is near-circular and [[orbital inclination|moderately-inclined]] (~8°), typical for the population of ''small'' [[cubewano|classical]] [[Kuiper Belt object]]s (KBO) but exceptional among the ''large'' KBO. [[20000 Varuna|Varuna]], {{mpl|2003 EL|61}} and {{dp|Makemake}} are all on highly inclined, more [[orbital eccentricity|eccentric]] orbits. The polar view compares the near-circular Quaoar's orbit to highly eccentric (e=0.25) orbit of {{dp|Pluto}} (Quaoar’s orbit in blue, Pluto’s in red, [[Neptune]] in grey). The spheres illustrate the current (April 2006) positions, relative sizes and colours. The [[perihelion|perihelia]] (q), [[aphelion|aphelia]] (Q) and the [[dates of passage]] are also marked. At 43 AU and a near-circular orbit, Quaoar is not significantly perturbed by Neptune, unlike Pluto which is in 2:3 [[orbital resonance]] with Neptune. The ecliptic view illustrates the relative inclinations of the orbits of Quaoar and Pluto. Note that Pluto's aphelion is beyond (and below) Quaoar's orbit, so that Pluto is closer to the [[Sun]] than Quaoar at some times of its orbit, and farther at others. As of 2008, Quaoar is currently only 13.9 AU<ref name>{{cite web |url=http://home.comcast.net/~kpheider/50000.txt |title=50000 Quaoar distance (AU) from Pluto |accessdate=2007-12-18}}</ref> from Pluto making it the closest large body to the Pluto-Charon system. By Kuiper Belt standards this is very close. == Physical characteristics == Quaoar is believed to be a mixture of rock and ice, like other [[Kuiper Belt Object]]s (KBOs); however its very low [[albedo]] (estimated at 0.1, but still much higher than that of {{dp|Varuna}} (0.04)) indicates that the ice has disappeared from Quaoar's outer layers. The surface is moderately red, meaning that the object is relatively more reflective in the red and near-infrared than in the blue. [[20000 Varuna]] and [[28978 Ixion]] are also moderately red in the spectral class. Larger KBOs are often much brighter because they are covered in more ice and have a higher albedo, and thus they present a neutral colour (see [[trans-Neptunian object#Physical characteristics|colour comparison]]). [[Image:Quaoar_hubble.jpg|thumb|250px|right|Hubble photo used to measure size of Quaoar.]] In 2004, scientists were surprised to find signs of [[crystal]]line [[ice]] on Quaoar, indicating that the temperature rose to at least &minus;160&nbsp;[[Celsius|°C]] (110&nbsp;K or &minus;260&nbsp;[[Fahrenheit|°F]]) sometime in the last ten million years<ref name="Jewitt2004"> {{cite journal | author=[[David Jewitt|Jewitt DC.]] and Luu J. | title=''Crystalline water ice on the Kuiper belt object (50000) Quaoar'' | journal=[[Nature (journal)|Nature]] | volume=432 | issue=7018 | year=2004 | pages=731–3 | doi=10.1038/nature03111}} PMID 15592406. [http://www.ifa.hawaii.edu/~jewitt/papers/2004/JL2004.pdf Reprint] on Jewitt's site (pdf)</ref>. Speculation began as to what could have caused Quaoar to heat up from its natural temperature of &minus;220&nbsp;°C (55&nbsp;K or &minus;360&nbsp;°F). Some have theorized that a barrage of mini-[[meteor]]s may have raised the temperature, but the most discussed theory speculates that [[Cryovolcano|cryovolcanism]] may be occurring, spurred by the decay of [[radioactive]] elements within Quaoar's core<ref name="JewittPage>[http://www.ifa.hawaii.edu/faculty/jewitt/quaoar.html Crystalline Ice on Kuiper Belt Object (50000) Quaoar] - article about crystalline ice on Quaoar</ref>. Since then (2006), crystalline water ice was also found on {{mpl-|136108|2003 EL|61}} but present in larger quantities and thought to be responsible for the very high albedo of that object (0.7)<ref name="Trujillo 2006">[[Chadwick A. Trujillo|C. A. Trujillo]], [[Michael Brown|Brown M.E.]], Barkume K., Shaller E., [[David Rabinowitz|Rabinowitz D.]] ''The Surface of {{mp|2003 EL|61}} in the Near Infrared''. The Astrophysical Journal, '''655''' (Feb. 2007), pp. 1172-1178 [http://arxiv.org/abs/astro-ph/0601618 Preprint]</ref>. More precise (2007) observations of Quaoar's near [[infrared spectrum]] indicate the presence of small (5%) quantity of (solid) [[methane]] and [[ethane]]<ref name="Quaoar_ShallerBrown2007" > E.L. Schaller, M.E. Brown ''Detection of Methane on Kuiper Belt Object (50000) Quaoar''. To appear in ApJ Letters (2007) [http://arxiv.org/abs/0710.3591 Preprint on arXiv.] </ref>. Given its [[boiling point]] (112 K), methane is a volatile ice at average Quaoar surface temperatures, unlike water ice or ethane (boiling point 185 K). Both models and observations suggest that only a few larger bodies ([[Pluto]], {{dp|Eris}}, {{dp|Makemake}}) can retain the volatile ices while the dominant population of small [[TNO]]s lost them. Quaoar with only small amounts of methane appears to be in an intermediary category<ref name="Quaoar_ShallerBrown2007"/>. If the ''[[New Horizons]]'' mission visits several Kuiper Belt Objects after visiting Pluto in [[2015]], our knowledge of the surfaces of small KBOs should improve but encounters with large objects seem unlikely. == Satellite == The discovery of a satellite of Quaoar was reported in IAUC 8812<!--- http://cfa-www.harvard.edu/iauc/08800/08812.html (subscription required during blackout period) ---> on [[22 February]] [[2007]] [http://www.johnstonsarchive.net/astro/astmoons/am-50000.html]. The orbit of this satellite has yet to be determined. The satellite was found at 0.35 [[arcsecond|arcsec]] from Quaoar with [[absolute magnitude|magnitude]] difference of 5.6<ref name="EKO51"> [http://www.boulder.swri.edu/ekonews/issues/past/n051/html/index.html Distant EKO] The Kuiper Belt Electronic newsletter, March 2007</ref>. Assuming an [[albedo#astronomical albedo|albedo]] similar to that of the primary the magnitude suggests the diameter of 100 km. ==References== <div class="references-small"><references/> </div> ==External links== {{commons|Quaoar}} * [http://www.chadtrujillo.com/quaoar/ Quaoar discoverers' webpage] *[http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Quaoar;orb=1;view=Far Orbital simulation] from JPL (Java) / [http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=Quaoar Ephemeris] * [http://www.nytimes.com/2004/12/09/science/09ice.html?ex=1260334800&amp;en=9326ecdbb6f20b0a&amp;ei=5090&amp;partner=rssuserland* Astronomers Contemplate Icy Volcanoes in Far Places] - [[New York Times]] article * [http://www.theage.com.au/articles/2002/10/07/1033538894512.html Quaoar, the newest planet . . . or is it?] - article in an Australian newspaper * [http://news.nationalgeographic.com/news/2002/10/1003_021007_quaoar.html New Planet-Shaped Body Found in Our Solar System ] - article in National Geographic * [http://www.cnn.com/2004/TECH/space/12/08/volcano.neptune/index.html Volcanism possible on planet-like Quaoar] - CNN.com * [http://www.nature.com/news/2004/041206/pf/041206-7_pf.html Chilly Quaoar had a warmer past ] - Nature.com article {{MinorPlanets Navigator|(49999) 2000 AW14|(50001) 2000 AK15}} {{Trans-Neptunian dwarf planets}} {{Small Solar System bodies}} {{Trans-Neptunian objects}} [[Category:Trans-Neptunian objects|Quaoar]] [[Category:Cubewanos|Quaoar]] [[Category:Discoveries by Michael E. Brown|Quaoar]] [[Category:Discoveries by Chad Trujillo|Quaoar]] [[als:(50000) Quaoar]] [[be-x-old:Квавар]] [[bg:50000 Кваоар]] [[ca:(50000) Quaoar]] [[cs:(50000) Quaoar]] [[da:Quaoar]] [[de:Quaoar (Asteroid)]] [[es:(50000) Quaoar]] [[eo:Kvaoaro]] [[fr:(50000) Quaoar]] [[ga:Quaoar]] [[gl:Quaoar]] [[ko:50000 콰오아]] [[it:50000 Quaoar]] [[hu:50000 Quaoar]] [[nl:Quaoar]] [[ja:クワオアー]] [[no:50000 Quaoar]] [[nn:50000 Quaoar]] [[pl:50000 Quaoar]] [[pt:50000 Quaoar]] [[ru:Квавар]] [[sk:50000 Quaoar]] [[fi:Quaoar]] [[sv:50000 Quaoar]] [[tr:50000 Quaoar]] [[zh:小行星50000]]