Centaur (asteroid)

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Orbits of known centaurs
color appearance of centaurs

A centaur , named after the centaurs of Greek mythology , is a member of a class of asteroids and comets that move around the Sun between the orbits of Jupiter and Neptune (see also List of Asteroids - Centaurs ). Research assumes that the centaurs descended from the Kuiper Belt .

Known centaurs

The three first centaurs discovered are

Largest known and confirmed centaur is

Note: The lost Centaur 1995 SN 55 could be larger and has an estimated diameter of almost 300 km. The centaur (523727) 2014 NW 65 could also be bigger than Chariklo.

For a long time the Kuiper Belt Planetoid (523736) 2014 QA 442 , which was also lost at the time, was considered a candidate for the largest centaur. In June 2017 it was rediscovered and thanks to the more precise orbit data it turned out that it is not a centaur, but an ordinary Kuiper belt asteroid.

In some centaurs, for example Pholus, frozen water has been discovered on the surface, in others, such as Chiron, no water ice has yet been detected. The centaurs are probably “extinct” comets , the volatile components of which were originally present, such as water ice or methane , have meanwhile more or less sublimed . However, for example, the centaurs Chiron and (60558) Echeclus , since a halo was discovered around them , are also classified as comets.

In 1998, a spectrum analysis by the Hubble Space Telescope revealed an impact crater on the surface of the centaur (8405) Asbolus , which is less than 10 million years old.

Fine ring systems have been discovered around the two largest confirmed centaurs Chariklo and Chiron.

The double centaur (65489) Ceto and its moon Phorcys form a close double planetoid system with two components of comparable size. Combined observations with the Infrared Spitzer Space Telescope and the Hubble Space Telescope made it possible to determine the diameter of Ceto at an estimated 174 (+ 16 / -18) km and the diameter of Phorcys at an estimated 132 (+ 6 / -14) km, below the Assumption of the same reflectivity of both components.

Mike Brown's website on possible dwarf planets also includes the centaurs Chariklo, (523727) 2014 NW 65 , Chiron and Ceto.

See also

literature

  • James M. Bauer, Tommy Grav, Erin Blauvelt, Amy Mainzer: Centaurs and Scattered Disk Objects in the Thermal Infrared: Analysis of WISE / NEOWISE Observations . In: The Astronomical Journal. No. 773/1 , 2013, arxiv : 1306.1862 .

Web links

Commons : Centaurs  - collection of images, videos and audio files

Individual evidence

  1. ↑ P. Santos-Sanz, E. Lellouch, S. Fornasier et al .: TNOs are Cool: A Survey of the Transneptunian Region IV . 2012, doi : 10.1051 / 0004-6361 / 201118541 , arxiv : 1202.1481 .
  2. ^ J. Horner, NW Evans, ME Bailey: Simulations of the Population of Centaurs I: The Bulk Statistics . In: Mon. Not. R. Astron. Soc. No. 000 , 2004, p. 1–15 , arxiv : astro-ph / 0407400 .
  3. ↑ Minor Planet Center: List Of Centaurs and Scattered-Disk Objects. ( minorplanetcenter.net ).
  4. ^ Wm. Robert Johnston: TNO / Centaur diameters and albedos In: Johnston's Archive. Archived from the original on October 22, 2008. 2008 ( johnstonsarchive.net ).
  5. ^ Joel Wm. Parker: Distant EKOs . In: The Kuiper Belt Electronic Newsletter, June 2017 . No. 109 , 2017 ( swri.edu [PDF]).
  6. ↑ Jane X. Luu, David Jewitt, CA Trujillo: Water Ice on 2060 Chiron and its Implications for Centaurs and Kuiper Belt Objects . In: The Astrophysical Journal . No. 531/2 , 2000, pp. L151 – L154 , arxiv : astro-ph / 0002094 .
  7. ↑ K. Wierzchos, M. Womack, G. Sarid: Carbon Monoxide in the Distantly Active Centaur (60558) 174P / Echeclus at 6 au . In: The Astronomical Journal . No. 153/5 , 2017, p. 8th ff ., arxiv : 1703.07660 .
  8. ↑ Hubble site .: Centaur's Bright Surface Spot Could be Crater of Fresh Ice . In: Hubble site . STScI-2000-31, 2004 ( hubblesite.org ).
  9. ↑ Braga-Ribas, F .; Sicardy, B .; Ortiz, JL; Snodgrass, C .; Roques, F .; Vieira-Martins, R .; Camargo, JIB; Assafin, M .; Duffard, R .; Jehin, E .; Pollock, J .; Leiva, R .; Emilio, M .; Machado, DI; Colazo, C .; Lellouch, E .; Skottfelt, J .; Gillon, M .; Ligier, N .; Maquet, L .; Benedetti-Rossi, G .; Gomes, AR; Kervella, P .; Monteiro, H .; Sfair, R .; Moutamid, ME; Tancredi, G .; Spagnotto, J .; Maury, A .; et al .: A ring system detected around the Centaur (10199) Chariklo . In: Nature . No. 508/7494 , 2014, pp. 72 ff ., arxiv : 1409.7259 .
  10. ↑ Ortiz, JL; Duffard, R .; Pinilla-Alonso, N .; Alvarez-Candal, A .; Santos-Sanz, P .; Morales, N .; Fernández-Valenzuela, E .; Licandro, J .; Campo Bagatin, A .; Thirouin, A .: Possible ring material around centaur (2060) Chiron . In: Astronomy & Astrophysics . No. 576 , 2015, p. A18 ., Arxiv : 1501.05911 .
  11. ↑ WM Grundy, JA Stansberry, KS Noll, DC Stephens et al .: The orbit, mass, size, albedo, and density of (65489) Ceto / Phorcys: A tidally-evolved binary Centaur . In: Icarus . No. 191 , 2007, p. 286 ff ., arxiv : 0704.1523 .
  12. ↑ Michael E. Brown: How many dwarf planets are there in the outer solar system? Ed .: California Institute of Technology. ( caltech.edu ).