WikiPortallus: Detached object (astronomy).html

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.¹² They 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 A total of 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 star⁷ 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

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). 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

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.

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 a lack of gravitational interaction with the outer planets disqualifies a trans-neptunian object from scattered disc membership, which would create an outer edge somewhere between Sedna and more conventional SDOs like Eris.

Known members

References

^ 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. arΧiv:0712.2198, http://arxiv.org/pdf/0712.2198.
^ 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)
^ Evidence for an Extended Scattered Disk?
^ ^a ^b Rodney S. Gomes; John J. Matese, Jack J. Lissauer (2006). "A distant planetary-mass solar companion may have produced distant detached objects". Icarus (Elsevier) 184 (2): 589–601. doi:10.1016/j.icarus.2006.05.026, http://adsabs.harvard.edu/abs/2006Icar..184..589G.
^ ^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". The Astronomical Journal 129, http://alpaca.as.arizona.edu/~trilling/des2.pdf.
^ ^a ^b Lykawka, Patryk Sofia & Mukai, Tadashi (July 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.
^ Morbidelli, Alessandro; Harold F. Levison (November 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, http://www.iop.org/EJ/abstract/1538-3881/128/5/2564/. Retrieved on 2 July 2008.
^ 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 on 2008-07-02.
^ 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)
^ W.M. Grundy, K.S. Noll and D.C. Stephens (July 2005). "Diverse albedos of small trans-Neptunian objects". Icarus (Elsevier) 176 (1): 184–191. doi:10.1016/j.icarus.2005.01.007, http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WGF-4FR4BS3-3&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=086bf515703846247c0819bb30f5b5f1. Retrieved on 22 March 2008. (arxiv.org)
^ ^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, http://64.233.183.104/search?q=cache:YBGHuSlg6a0J:www.gps.caltech.edu/~mbrown/papers/ps/volatiles.pdf+VOLATILE+LOSS+AND+RETENTION+ON+KUIPER+BELT+OBJECTS&hl=en&ct=clnk&cd=1&gl=uk&lr=lang_en. Retrieved on 2 April 2008. (PDF)
^ 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

Detached object (astronomy).html

Contents

Orbits

Classification

Known members

References