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Plutinos are named after dwarf planet Pluto.
Plutinos, in astronomy, are Trans-Neptunian objects in 2:3 mean motion resonance with Neptune. Plutinos are named after Pluto. Plutinos follow an orbit trapped in the same resonance, with the Italian diminutive suffix -ino. The name refers only to the orbital resonance and does not imply common physical characteristics; it was invented to describe those bodies smaller than Pluto with the resonance (hence the diminutive) but now includes Pluto itself.
Plutinos form the inner part of the Kuiper belt and represent about a quarter of the known Kuiper belt objects (KBOs). Aside from Pluto itself, the first plutino, 1993 RO, was discovered on September 16, 1993.
The largest plutinos include Pluto, 90482 Orcus, 28978 Ixion, 38083 Rhadamanthus, and 38628 Huya.
Origin of plutinos.
It is thought that objects that are currently in mean orbital resonances with Neptune followed initially independent heliocentric paths. During Neptune’s migration (see Kuiper Belt), the objects have been caught into the resonances sweeping outward.
Orbital characteristics of Plutinos.
While the majority of plutinos have low orbital inclinations, a substantial number of them follow orbits similar to that of Pluto, with inclinations in the 10-25o range and eccentricities around 0.2-0.25, resulting in perihelions inside (or close to) the orbit of Neptune and aphelions close to the main Kuiper belt's outer edge (where objects have 1:2 resonance with Neptune).
The orbital periods of plutinos cluster around 247.3 years (1.5 x Neptune's orbital period), varying by at most a few years from this value.
Unusual plutinos include:
See also the comparison with the distribution of the cubewanos.
Long-term stability of plutinos.
The gravitational influence of Pluto is usually neglected given its 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 be driven out of the resonance by interactions with Pluto. Numerical simulations suggest that Plutinos with the eccentricity 10%-30% smaller or bigger than that of Pluto are not stable in Ga timescales.
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