Plutino

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In astronomy, the plutinos are a dynamical group of trans-Neptunian objects that orbit in 2:3 mean-motion resonance with Neptune. This means that for every two orbits a plutino makes, Neptune orbits three times. The dwarf planet Pluto is the largest member as well as the namesake of this group. The next largest members are Template:Dp, Achlys, and Template:Dp. Plutinos are named after mythological creatures associated with the underworld.

Plutinos form the inner part of the Kuiper belt and represent about a quarter of the known Kuiper belt objects. They are also the most populous known class of resonant trans-Neptunian objects (also see adjunct box with hierarchical listing). The first plutino after Pluto itself, (385185) 1993 RO, was discovered on September 16, 1993.

Orbits

File:ThePlutinos Size Albedo Color2.svg
Some of the largest known plutinos compared in size, albedo and colour

Origin

It is thought that the objects that are currently in mean orbital resonances with Neptune initially followed a variety of independent heliocentric paths. As Neptune migrated outward early in the Solar System's history (see origins of the Kuiper belt), the bodies it approached would have been scattered; during this process, some of them would have been captured into resonances.[1] The 3:2 resonance is a low-order resonance and is thus the strongest and most stable among all resonances.[2] This is the primary reason it has a larger population than the other Neptunian resonances encountered in the Kuiper Belt. The cloud of low-inclination bodies beyond 40 AU is the cubewano family, while bodies with higher eccentricities (0.05 to 0.34) and semi-major axes close to the 3:2 Neptune resonance are primarily plutinos.[3]

Orbital characteristics

File:Plutino distributions and sizes.png
The distribution of Plutinos, and relative sizes, drawn 1 million times larger.

While the majority of plutinos have relatively low orbital inclinations, a significant fraction of these objects follow orbits similar to that of Pluto, with inclinations in the 10–25° range and eccentricities around 0.2–0.25; such orbits result in many of these objects having perihelia close to or even inside Neptune's orbit, while simultaneously having aphelia that bring them close to the main Kuiper belt's outer edge (where objects in a 1:2 resonance with Neptune, the twotinos, are found).

The orbital periods of plutinos cluster around 247.3 years (1.5 × Neptune's orbital period), varying by at most a few years from this value.

Unusual plutinos include:

  • [[List of unnumbered trans-Neptunian objects: 2005#2005 TV189|Template:Mp]], which follows the most highly inclined orbit (34.5°)
  • Template:Mpl, which has the most elliptical orbit (its eccentricity is 0.33), with the perihelion halfway between Uranus and Neptune
  • Template:Mpl following a quasi-circular orbit
  • [[List of unnumbered trans-Neptunian objects: 2002#2002 VX130|Template:Mp]] lying almost perfectly on the ecliptic (inclination less than 1.5°)
  • 15810 Arawn, a quasi-satellite of Pluto[4]

See also the comparison with the distribution of the cubewanos.

Long-term stability

Pluto's influence on the other plutinos has historically been neglected due to its relatively small mass. However, the resonance width (the range of semi-axes compatible with the resonance) is very narrow and only a few times larger than Pluto's Hill sphere (gravitational influence). Consequently, depending on the original eccentricity, some plutinos will eventually be driven out of the resonance by interactions with Pluto.[5] Numerical simulations suggest that the orbits of plutinos with an eccentricity 10%–30% smaller or larger than that of Pluto are not stable over billion-year timescales.[6]

Orbital diagrams

Brightest objects

The plutinos brighter than HV=6 include:

Object a
(AU)		 q
(AU)		 i
(°)		 H Diameter
(km)		 Mass
(1020 kg)		 Albedo V−R Discovery
year		 Discoverer Refs
134340 Pluto 39.3 29.7 17.1 −0.7 2322 130 0.49–0.66 1930 Clyde Tombaugh JPL
90482 Orcus 39.2 30.3 20.6 Template:Val Template:Val Template:Val Template:Val 0.37 2004 M. Brown,
C. Trujillo,
D. Rabinowitz		 JPL
208996 Achlys 39.4 32.3 13.6 Template:Val Template:Val ≈ 3 Template:Val Template:Val 2003 M. Brown,
C. Trujillo		 JPL
28978 Ixion 39.7 30.1 19.6 Template:Val Template:Val ≈ 3 Template:Val 0.61 2001 Deep Ecliptic Survey JPL
Template:Mpl 39.5 31.3 13.6 Template:Val ≈ 380–680 ? ? ? 2017 D. J. Tholen,
S. S. Sheppard,
C. Trujillo		 JPL
Template:Mpl 39.3 36.4 14.8 Template:Val Template:Val ≈ 1.5 Template:Val Template:Val 2003 NEAT JPL
Template:Mpl 39.2 30.4 12.0 Template:Val ≈ 600 ≈ 2 ? Template:Val 2001 M. Brown,
C. Trujillo,
D. Rabinowitz		 JPL
Template:Mpl 39.5 36.0 15.4 Template:Val ≈ 240–670 ? ? ? 2014 Pan-STARRS JPL
Template:Mpl 39.5 36.7 19.4 Template:Val ≈ 240–670 ? ? ? 2014 Pan-STARRS JPL
38628 Huya 39.4 28.5 15.5 Template:Val Template:Val ≈ 0.5 Template:Val Template:Val 2000 Ignacio Ferrin JPL
Template:Mpl 39.3 27.4 12.0 Template:Val Template:Val ≈ 0.012 Template:Val 2006 Marc W. Buie JPL
Template:Mpl 39.3 34.5 13.3 Template:Val Template:Val ≈ 1.7 Template:Val Template:Val 2001 M.W.Buie JPL
Template:Mpl 39.3 34.9 22.4 Template:Val Template:Val ≈ 0.7 Template:Val Template:Val 2001 Marc W. Buie JPL
47171 Lempo 39.3 30.6 8.4 Template:Val Template:Val
(triple)		 Template:Val Template:Val Template:Val 1999 E. P. Rubenstein,
L.-G. Strolger		 JPL
Template:Mpl 39.3 31.2 14.0 Template:Val Template:Val ≈ 0.16 Template:Val 2002 Marc W. Buie JPL
Template:Mpl 39.3 28.9 14.0 Template:Val Template:Val ≈ 1 Template:Val Template:Val 2002 NEAT JPL
Template:Mpl 39.4 30.4 16.3 Template:Val Template:Val ≈ 0.15 Template:Val Template:Val 2002 NEAT JPL

(link to all of the orbits of these objects listed above are here)

See also

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References

Template:Reflist Template:Refbegin

  • 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., Template:ISBN (2006). Preprint of the article (pdf)
  • Bernstein G.M., Trilling D.E., Allen R.L., Brown K.E, Holman M., Malhotra R. The size Distribution of transneptunian bodies. The Astronomical Journal, 128, 1364–1390. preprint on arXiv
  • Minor Planet Center Orbit database (MPCORB) as of 2008-10-05.
  • Minor Planet Circular 2008-S05 (October 2008) Distant Minor planets was used for orbit classification.

Template:Refend

External links

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