Inastronomy, theplutinos are adynamical group oftrans-Neptunian objects that orbit in 2:3mean-motion resonance withNeptune. This means that for every two orbits a plutino makes, Neptune orbits three times. The dwarf planetPluto is the largest member as well as the namesake of this group. The next largest members areOrcus,Achlys, andIxion. Plutinosare named after mythological creatures associated with the underworld.
Plutinos form the inner part of theKuiper belt and represent about a quarter of the knownKuiper belt objects. They are also the most populous known class ofresonant 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.
It is thought that the objects that are currently in meanorbital resonances with Neptune initially followed a variety of independent heliocentric paths. As Neptune migrated outward early in the Solar System's history (seeorigins 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 40AU is thecubewano family, while bodies with highereccentricities (0.05 to 0.34) andsemi-major axes close to the 3:2 Neptune resonance are primarily plutinos.[3]
While the majority of plutinos have relatively loworbital 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 havingperihelia close to or even inside Neptune's orbit, while simultaneously havingaphelia that bring them close to the mainKuiper 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:
See also the comparison with thedistribution of the cubewanos.
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'sHill sphere (gravitational influence). Consequently, depending on the original eccentricity, some plutinos will eventually be driven out of the resonance byinteractions 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]
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 | 2.31±0.03 | 917±25 | 6.32±0.05 | 0.28±0.06 | 0.37 | 2004 | M. Brown, C. Trujillo, D. Rabinowitz | JPL |
| 208996 Achlys | 39.4 | 32.3 | 13.6 | 3.74±0.08 | 727.0+61.9 −66.5 | ≈ 3 | 0.107+0.023 −0.016 | 0.38±0.04 | 2003 | M. Brown, C. Trujillo | JPL |
| 28978 Ixion | 39.7 | 30.1 | 19.6 | 3.828±0.039 | 617+19 −20 | ≈ 3 | 0.141±0.011 | 0.61 | 2001 | Deep Ecliptic Survey | JPL |
| (678191) 2017 OF69 | 39.5 | 31.3 | 13.6 | 4.091±0.12 | ≈ 380–680 | ? | ? | ? | 2017 | D. J. Tholen, S. S. Sheppard, C. Trujillo | JPL |
| (84922) 2003 VS2 | 39.3 | 36.4 | 14.8 | 4.1±0.38 | 523.0+35.1 −34.4 | ≈ 1.5 | 0.147+0.063 −0.043 | 0.59±0.02 | 2003 | NEAT | JPL |
| (455502) 2003 UZ413 | 39.2 | 30.4 | 12.0 | 4.38±0.05 | ≈ 600 | ≈ 2 | ? | 0.46±0.06 | 2001 | M. Brown, C. Trujillo, D. Rabinowitz | JPL |
| (556068) 2014 JR80 | 39.5 | 36.0 | 15.4 | 4.9 | ≈ 240–670 | ? | ? | ? | 2014 | Pan-STARRS | JPL |
| (578993) 2014 JP80 | 39.5 | 36.7 | 19.4 | 4.9 | ≈ 240–670 | ? | ? | ? | 2014 | Pan-STARRS | JPL |
| 38628 Huya | 39.4 | 28.5 | 15.5 | 5.04±0.03 | 406±16 | ≈ 0.5 | 0.083±0.004 | 0.57±0.09 | 2000 | Ignacio Ferrin | JPL |
| (469987) 2006 HJ123 | 39.3 | 27.4 | 12.0 | 5.32±0.66 | 283.1+142.3 −110.8 | ≈ 0.012 | 0.136+0.308 −0.089 | 2006 | Marc W. Buie | JPL | |
| (612533) 2002 XV93 | 39.3 | 34.5 | 13.3 | 5.42±0.46 | 549.2+21.7 −23.0 | ≈ 1.7 | 0.040+0.020 −0.015 | 0.37±0.02 | 2001 | M.W.Buie | JPL |
| (469372) 2001 QF298 | 39.3 | 34.9 | 22.4 | 5.43±0.07 | 408.2+40.2 −44.9 | ≈ 0.7 | 0.071+0.020 −0.014 | 0.39±0.06 | 2001 | Marc W. Buie | JPL |
| 47171 Lempo | 39.3 | 30.6 | 8.4 | 5.41±0.10 | 393.1+25.2 −26.8 (triple) | 0.1275±0.0006 | 0.079+0.013 −0.011 | 0.70±0.03 | 1999 | E. P. Rubenstein, L.-G. Strolger | JPL |
| (307463) 2002 VU130 | 39.3 | 31.2 | 14.0 | 5.47±0.83 | 252.9+33.6 −31.3 | ≈ 0.16 | 0.179+0.202 −0.103 | 2002 | Marc W. Buie | JPL | |
| (84719) 2002 VR128 | 39.3 | 28.9 | 14.0 | 5.58±0.37 | 448.5+42.1 −43.2 | ≈ 1 | 0.052+0.027 −0.018 | 0.60±0.02 | 2002 | NEAT | JPL |
| (55638) 2002 VE95 | 39.4 | 30.4 | 16.3 | 5.70±0.06 | 249.8+13.5 −13.1 | ≈ 0.15 | 0.149+0.019 −0.016 | 0.72±0.05 | 2002 | NEAT | JPL |
(link to all of the orbits of these objects listed above arehere)
