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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, Template:Mpl, 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.
OrbitsEdit
OriginEdit
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.<ref name="Malhotra1995">Template:Cite journal</ref> The 3:2 resonance is a low-order resonance and is thus the strongest and most stable among all resonances.<ref>Template:Cite journal</ref> 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 semimajor axes close to the 3:2 Neptune resonance are primarily plutinos.<ref>Template:Cite book</ref>
Orbital characteristicsEdit
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<ref name=analemma>Template:Cite journal</ref>
See also the comparison with the distribution of the cubewanos.
Long-term stabilityEdit
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.<ref name=wan2001>Template:Cite journal</ref> Numerical simulations suggest that the orbits of plutinos with an eccentricity 10%–30% smaller or larger than that of Pluto are not stable over Ga timescales.<ref name="Yu1999">Template:Cite journal</ref>
Orbital diagramsEdit
- OrcusandPlutoRotatingFrame.gif
The motions of Orcus and Pluto in a rotating frame with a period equal to Neptune's orbital period (holding Neptune stationary). Pluto is grey, Orcus is red, and Neptune is the white (stationary) dot at 5 o'clock. Uranus is blue, Saturn yellow, and Jupiter red.
- TheKuiperBelt 60AU LargePlutinos.svg
Orbits and sizes of the larger plutinos (and the reference non-plutino Template:Mpl-). Orbital eccentricity is represented by segments extending horizontally from perihelion to aphelion; inclination is shown on the vertical axis.
- TheKuiperBelt 60AU Plutinos distribution.svg
The distribution of plutinos (and the reference non-plutino Template:Mp). Small inserts show histograms for the distributions of orbital inclination and eccentricity.
Brightest objectsEdit
The plutinos brighter than HV=6 include:
(link to all of the orbits of these objects listed above are here)
See alsoEdit
ReferencesEdit
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- 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.
External linksEdit
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