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Detached object

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Trans-Neptunian Objects beyond 100AU: SDO (in grey) and Detached objects (in white)

Detached objects are nonclassical trans-Neptunian objects (TNOs) with a perihelion too far away from Neptune to be significantly influenced by it, and so appear to be “detached” from the solar system.[1][2] (Most trans-Neptunian objects are either close to their original orbit or have been perturbed onto their current orbit by the known gas giant planets.) Detached objects have also been referred to as extended scattered disc objects (E-SDO),[3] Distant Detached Objects (DDO)[4] or Scattered–Extended in the formal classification by Deep Ecliptic Survey.[5] At least nine such bodies have been securely identified.[6]

Orbits

Detached objects generally have highly elliptical, very large orbits with semi-major axes of up to a few hundred AU. Such orbits cannot have been created by gravitational scattering by the gas giants (in particular, Neptune). Instead, a number of explanations have been put forward, including an encounter with a passing star[7] or a distant, planet-sized object.[4] The classification suggested by the Deep Ecliptic Survey team introduces a formal distinction between Scattered-Near objects (which could be scattered by Neptune) and Scattered-Extended objects (e.g. 90377 Sedna) using a Tisserand's parameter value of 3.[5]

Classification

Types of distant minor planets

Detached objects are one of four distinct dynamical classes of TNO; the other three classes are classical Kuiper belt objects, resonant objects and scattered disc objects (SDO). Detached objects generally have a perihelion distance greater than 40 astronomical units (AU) deterring strong interactions with Neptune. However, there are no clear boundaries between the scattered and detached regions, since both can coexist as TNOs in an intermediate region with perihelion distance between 37 and 40 AU.[6] One such intermediate body with a well determined orbit is (120132) 2003 FY128.

The discovery of 90377 Sedna together with a few other objects such as 2000 CR105 and 2004 XR190 (also known as "Buffy") has motivated discussion of a category of distant objects that may also be inner Oort cloud objects or (more likely) transitional objects between the scattered disc and the inner Oort cloud.[citation needed]

Although Sedna is officially considered a scattered disc object by the MPC, its discoverer Michael E. Brown has suggested that because its perihelion distance of 76 AU is too distant to be affected by the gravitational attraction of the outer planets it should be considered an inner Oort cloud object rather than a member of the scattered disc.[8] This classification of Sedna as a Detached object is accepted in recent publications.[9]

This line of thinking suggests that the lack of a significant gravitational interaction with the outer planets creates an extended–outer group starting somewhere between Sedna (perihelion 76AU) and more conventional SDOs like Eris (perihelion 37AU). Eris is listed as a Scattered–Near object by the Deep Ecliptic Survey.[10]

One of the problems with defining this extended category is that weak resonances may exist and would be difficult to prove due to chaotic planetary perturbations and the current lack of accuracy in the orbits of these distant objects. These objects have orbital periods of more than 300 years and most have only been observed over a short observation arc of a couple years. Due to their great distance and slow movement against background stars, it may be decades before most of these distant orbits are determined well enough to confidently confirm or rule out a resonance. Further improvement in the orbit and potential resonance of these objects will help to understand the migration of the giant planets and the formation of the solar system.[citation needed]

Simulations by Emel’yanenko and Kiseleva in 2007 show that many distant objects could be in resonance with Neptune. They show a 10% chance that 2000 CR105 is in a 20:1 resonance, a 38% chance that 2003 QK91 is in a 10:3 resonance, and a 84% likelihood that (82075) 2000 YW134 is in a 8:3 resonance.[11] The dwarf planet candidate (145480) 2005 TB190 appears to have less than a 1% chance of being in a 4:1 resonance.[11]

Candidates

This is a list of known objects by decreasing perihelion, that could not be easily scattered by Neptune's current orbit and therefore are likely to be detached objects:

Number
[12]
 Name
 Diameter
(km)
 H
 Perihelion
(AU)
 Aphelion
(AU)
 Year
discovered
 Discoverer(s)
 Diameter
method
 Type
90377 Sedna 1200–1600 1.6 76.1 975.5 2003 Brown, Trujillo, Rabinowitz thermal detached[13]
2004 XR190 335–850 4.5 52.3 61.8 2004 Lynne Jones et al. assumed detached[14][15]
2004 VN112 130–300 6.4 47.3 614 2004 ??? assumed detached[16]
145480 2005 TB190 ~500 4.7 46.2 106.5 2005 Becker, A. C. et al. assumed detached
148209 2000 CR105 ~250 6.1 44.3 397 2000 Lowell Observatory assumed detached[14]
2003 UY291 ~150 7.3 41.2 57.1 2003 Pittichova, J et al. assumed classical?[17]
82075 2000 YW134 ~500 4.7 41.0 73.9 2000 Spacewatch assumed 8:3[18]
48639 1995 TL8 ~350 5.2 40.0 64.5 1995 A. Gleason assumed detached
2003 QK91 ~180 6.9 38.4 98.5 2003 Elliot, J et al. assumed detached[19]
2003 FZ129 ~150 7.3 38.0 85.6 2003 ??? assumed detached[20]
134210 2005 PQ21 ~200 6.7 37.6 87.6 2005 Cerro Tololo assumed detached[21]
2006 QH181 ~765 3.8 37.6 97.0 2006 ??? assumed detached or 5:1?[22]
120132 2003 FY128 ~440 4.8 37.0 61.7 2003 N.E.A.T. assumed detached[23]
2006 HX122 ~290 5.9 36.4 102.6 2006 ??? assumed detached[24] or 7:2?[25]

See also

References

  1. ^ P. S. Lykawka; T. Mukai (2008). "An Outer Planet Beyond Pluto and the Origin of the Trans-Neptunian Belt Architecture". Astronomical Journal. 135: 1161. doi:10.1088/0004-6256/135/4/1161. arXiv:0712.2198.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. ^ D.Jewitt, A.Delsanti The Solar System Beyond The Planets in Solar System Update : Topical and Timely Reviews in Solar System Sciences , Springer-Praxis Ed., ISBN 3-540-26056-0 (2006) Preprint of the article (pdf)
  3. ^ Evidence for an Extended Scattered Disk?
  4. ^ a b Rodney S. Gomes (2006). "A distant planetary-mass solar companion may have produced distant detached objects". Icarus. 184 (2). Elsevier: 589–601. doi:10.1016/j.icarus.2006.05.026. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help) Cite error: The named reference "Gomez 2006" was defined multiple times with different content (see the help page).
  5. ^ a b J. L. Elliot, S. D. Kern, K. B. Clancy, A. A. S. Gulbis, R. L. Millis, M. W. Buie, L. H. Wasserman, E. I. Chiang, A. B. Jordan, D. E. Trilling, and K. J. Meech (2006). "The Deep Ecliptic Survey: A Search for Kuiper Belt Objects and Centaurs. II. Dynamical Classification, the Kuiper Belt Plane, and the Core Population" (PDF). The Astronomical Journal. 129. {{cite journal}}: Unknown parameter |formal= ignored (help)CS1 maint: multiple names: authors list (link) Cite error: The named reference "DES_Elliot2006" was defined multiple times with different content (see the help page).
  6. ^ a b Lykawka, Patryk Sofia & Mukai, Tadashi (2007). "Dynamical classification of trans-neptunian objects: Probing their origin, evolution, and interrelation". Icarus. 189 (1): 213–232. doi:10.1016/j.icarus.2007.01.001. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  7. ^ Morbidelli, Alessandro (2004). "Scenarios for the Origin of the Orbits of the Trans-Neptunian Objects 2000 CR105 and 2003 VB12". The Astronomical Journal. 128 (5): 2564–2576. doi:10.1086/424617. Retrieved 2008-07-02. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  8. ^ Brown, Michael E. "Sedna (The coldest most distant place known in the solar system; possibly the first object in the long-hypothesized Oort cloud)". California Institute of Technology, Department of Geological Sciences. Retrieved 2008-07-02.
  9. ^ D.Jewitt, A. Moro-Martın, P.Lacerda The Kuiper Belt and Other Debris Disks to appear in Astrophysics in the Next Decade, Springer Verlag (2009). Preprint of the article (pdf)
  10. ^ Marc W. Buie (2007-12-28). "Orbit Fit and Astrometric record for 136199". SwRI (Space Science Department). Retrieved 2009-01-25.
  11. ^ a b Emel’yanenko, V. V (2008). "Resonant motion of trans-Neptunian objects in high-eccentricity orbits". Astronomy Letters. 34: 271–279. Retrieved 2009-01-25. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)(subscription required)
  12. ^ Objects with a MPC number have a more secured orbit than objects with only a provisional designation.
  13. ^ W.M. Grundy, K.S. Noll and D.C. Stephens (July 2005). "Diverse albedos of small trans-Neptunian objects". Icarus. 176 (1). Elsevier: 184–191. doi:10.1016/j.icarus.2005.01.007. Retrieved 2008-03-22. (arxiv.org)
  14. ^ a b E. L. Schaller and M. E. Brown (2007). "Volatile loss and retention on Kuiper belt objects". Astrophysical Journal. 659: I.61–I.64. doi:10.1086/516709. Retrieved 2008-04-02. (PDF)
  15. ^ R. L. Allen, B. Gladman (2006). "Discovery of a low-eccentricity, high-inclination Kuiper Belt object at 58 AU". The Astrophysical Journal. 640. Discovery paper. Preprint
  16. ^ Marc W. Buie (2007-11-08). "Orbit Fit and Astrometric record for 04VN112". SwRI (Space Science Department). Retrieved 2008-07-17.
  17. ^ Marc W. Buie (2005-12-02). "Orbit Fit and Astrometric record for 03UY291". SwRI (Space Science Department). Retrieved 2009-01-22.
  18. ^ Marc W. Buie (2004-04-16). "Orbit Fit and Astrometric record for 82075". SwRI (Space Science Department). Retrieved 2008-07-18.
  19. ^ Marc W. Buie (2008-06-07). "Orbit Fit and Astrometric record for 03QK91". SwRI (Space Science Department). Retrieved 2009-01-27.
  20. ^ Marc W. Buie (2005-07-10). "Orbit Fit and Astrometric record for 03FZ129". SwRI (Space Science Department). Retrieved 2009-01-27.
  21. ^ Marc W. Buie (2006-07-30). "Orbit Fit and Astrometric record for 134210". SwRI (Space Science Department). Retrieved 2009-01-24.
  22. ^ Marc W. Buie (2008-03-05). "Orbit Fit and Astrometric record for 06QH181". SwRI (Space Science Department). Retrieved 2008-07-29.
  23. ^ Marc W. Buie (2006-04-02). "Orbit Fit and Astrometric record for 120132". SwRI (Space Science Department). Retrieved 2009-01-22.
  24. ^ Marc W. Buie (2007-07-16). "Orbit Fit and Astrometric record for 06HX122". SwRI (Space Science Department). Retrieved 2009-01-23.
  25. ^ "MPEC 2008-K28 : 2006 HX122". Minor Planet Center. 2008-05-23. Retrieved 2009-01-30.
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