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2004 Xr190

2004 XR190
Discovered by Lynne Jones
Brett Gladman
John J. Kavelaars
Jean-Marc Petit
Joel Parker
Phil Nicholson
Discovery date 11 December 2004
MPC designation 2004 XR190
detached object
Orbital characteristics[3]
Epoch 2457000.5 (2014-Dec-09.0)
Aphelion 64.032 ± 0.016 AU
Perihelion 51.394 ± 0.046 AU
57.713 ± 0.015 AU
Eccentricity 0.10949 ± 0.00083
438.45 ± 0.17 yr
(160,143 ± 64 d)
277.64 ± 0.17°
Inclination 46.5950 ± 0.0017°
252.362839 ± 0.000059° (Ω)
281.64 ± 0.11° (ω)
Physical characteristics
Dimensions 425–850 km (albedo 0.16–0.04)[4]
335–530 km (albedo 0.25–0.10)[5]
Albedo < 0.25?

2004 XR190 is a possible dwarf planet[7] located in the scattered disc. It has a highly inclined low-eccentricity orbit. It was discovered in December 2004.


  • History 1
    • Discovery 1.1
    • Naming 1.2
  • Orbit 2
  • Size 3
  • References 4
  • External links 5



2004 XR190 was discovered on 11 December 2004. It was discovered by astronomers led by Lynne Jones of the University of British Columbia as part of the Canada–France Ecliptic Plane Survey (CFEPS) using the Canada–France–Hawaii Telescope (CFHT) near the ecliptic. In 2015, six precovery images from 2002 and 2003 were found in Sloan Digital Sky Survey data.


2004 XR190 was nicknamed "Buffy" by the discovery team, after the fictional vampire slayer,[8] and proposed a different official name to the IAU.


Considered a detached object,[9][10] 2004 XR190 is particularly unusual for two reasons. With an inclination of 47 degrees, it is the largest possible dwarf planet that has an inclination larger than 45 degrees,[11] traveling further "up and down" than "left to right" around the Sun when viewed edge-on along the ecliptic. Second, it has an unusually circular orbit for a scattered-disc object (SDO). Although it is thought that traditional scattered-disc objects have been ejected into their current orbits by gravitational interactions with Neptune, the low eccentricity of its orbit and the distance of its perihelion (SDOs generally have highly eccentric orbits and perihelia less than 38 AU) seems hard to reconcile with such celestial mechanics. This has led to some uncertainty as to the current theoretical understanding of the outer Solar System. The theories include close stellar passages, rogue planets/planetary embryos in the early Kuiper belt, and resonance interaction with an outward-migrating Neptune. The Kozai mechanism is capable of transferring orbital eccentricity to a higher inclination.[4]

2004 XR190 came to aphelion around 1901.[12] Other than long-period comets, it is currently about the thirteenth-most-distant known large body (57.5 AU) in the Solar System with a well-known orbit, after Eris and Dysnomia (96.3 AU), 2007 OR10 (87.4 AU), Sedna (85.9 AU), 2014 FC69 (84.0 AU), 2006 QH181 (83.3 AU), 2012 VP113 (83.3 AU), 2013 FY27 (80.3 AU), 2010 GB174 (70.5 AU), 2000 CR105 (60.3 AU), 2003 QX113 (59.8 AU), and 2008 ST291 (59.6 AU).[13]


2004 XR190 has a diameter estimated at around 500 kilometres (310 mi), roughly a quarter the size of Pluto, and it orbits between 51 and 64 AU (7.7 and 9.5 billion kilometers) from the Sun.


  1. ^ "MPEC 2005-X72 : 2004 XR190". IAU Minor Planet Center. 2005-12-12. Retrieved 2014-04-06.  (K04XJ0R)
  2. ^ "2004 XR190 Orbit" (arc=2221 days over 5 oppositions). IAU Minor Planet Center. Retrieved 2014-04-06. 
  3. ^ a b "JPL Small-Body Database Browser: (2004 XR190)" (2011-01-10 last obs). Retrieved 2014-03-30. 
  4. ^ a b R. L. Allen; B. Gladman (2006). "Discovery of a low-eccentricity, high-inclination Kuiper belt object at 58 AU". The Astrophysical Journal 640: L83.   (Discovery paper)
  5. ^ E. L. Schaller & M. E. Brown (2007). "Volatile loss and retention on Kuiper belt objects" (PDF). Astrophysical Journal 659: I.61–I.64.  
  6. ^ Ephemerides"190"AstDys 2004 XR. Department of Mathematics, University of Pisa, Italy. Archived from the original on 26 May 2011. Retrieved 2011-05-16. 
  7. ^  
  8. ^ Maggie McKee. "Strange new object found at edge of Solar System".  
  9. ^ Jewitt, David, Morbidelli, Alessandro, & Rauer, Heike. (2007). Trans-Neptunian Objects and Comets: Saas-Fee Advanced Course 35. Swiss Society for Astrophysics and Astronomy. Berlin: Springer. ISBN 3-540-71957-1.
  10. ^ Lykawka, Patryk Sofia & Mukai, Tadashi. (2007). Dynamical classification of trans-neptunian objects: Probing their origin, evolution, and interrelation. Icarus Volume 189, Issue 1, July, Pages 213–232. doi:10.1016/j.icarus.2007.01.001.
  11. ^ "JPL Small-Body Database Search Engine: H < 6.5 (mag)". JPL Solar System Dynamics. Retrieved 2014-03-27. 
  12. ^ "Horizon Online Ephemeris System". California Institute of Technology, Jet Propulsion Laboratory. Retrieved 2009-03-23. 
  13. ^ AstDyS-2 list of minor planets more than 57.0 AU from the Sun

External links

Media related to at Wikimedia Commons

  • MPEC circular detailing discovery
  • Discovery webpage by research team
  • Maggie McKee (13 December 2005). "Strange new object found at edge of Solar System".  
  • Canada-France-Hawaii Telescope Legacy Survey
  • Orbital simulation from JPL (Java) / Ephemeris
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