Plutino

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. 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). Aside from Pluto itself, the first plutino, (385185) 1993 RO, was discovered on September 16, 1993.

Orbits

Some of the first 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 semimajor axes close to the 3:2 Neptune resonance are primarily plutinos.[3]

Orbital characteristics

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:

  • 2005 TV189, which follows the most highly inclined orbit (34.5°)
  • (15875) 1996 TP66, which has the most elliptical orbit (its eccentricity is 0.33), with the perihelion halfway between Uranus and Neptune
  • (470308) 2007 JH43 following a quasi-circular orbit
  • 2002 VX130 lying almost perfectly on the ecliptic (inclination less than 1.5°)

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.[4] 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.[5]

Orbital diagrams

Brightest objects

The plutinos brighter than HV=6 include:

Objecta
(AU)
q
(AU)
i
(°)
HDiameter
(km)
Mass
(1020 kg)
AlbedoV−RDiscovery
year
DiscovererRefs
134340 Pluto39.329.717.1−0.723221300.49–0.661930Clyde TombaughJPL
90482 Orcus39.230.320.62.31±0.03917±256.32±0.050.28±0.060.372004M. Brown,
C. Trujillo,
D. Rabinowitz
JPL
(208996) 2003 AZ8439.432.313.63.74±0.08727.0+61.9
−66.5
30.107+0.023
−0.016
0.38±0.042003M. Brown,
C. Trujillo
JPL
28978 Ixion39.730.119.63.828±0.039617+19
−20
30.141±0.0110.612001Deep Ecliptic SurveyJPL
2017 OF6939.531.313.64.091±0.12380–680???2017D. J. Tholen,
S. S. Sheppard,
C. Trujillo
JPL
(84922) 2003 VS239.336.414.84.1±0.38523.0+35.1
−34.4
1.50.147+0.063
−0.043
0.59±0.022003NEATJPL
(455502) 2003 UZ41339.230.412.04.38±0.056002?0.46±0.062001M. Brown,
C. Trujillo,
D. Rabinowitz
JPL
2014 JR8039.536.015.44.9240–670???2014Pan-STARRSJPL
2014 JP8039.536.719.44.9240–670???2014Pan-STARRSJPL
38628 Huya39.428.515.55.04±0.03406±160.50.083±0.0040.57±0.092000Ignacio FerrinJPL
(469987) 2006 HJ12339.327.412.05.32±0.66283.1+142.3
−110.8
0.0120.136+0.308
−0.089
2006Marc W. BuieJPL
2002 XV9339.334.513.35.42±0.46549.2+21.7
−23.0
1.70.040+0.020
−0.015
0.37±0.022001M.W.BuieJPL
(469372) 2001 QF29839.334.922.45.43±0.07408.2+40.2
−44.9
0.70.071+0.020
−0.014
0.39±0.062001Marc W. BuieJPL
47171 Lempo39.330.68.45.41±0.10393.1+25.2
−26.8

(triple)
0.1275±0.00060.079+0.013
−0.011
0.70±0.031999E. P. Rubenstein,
L.-G. Strolger
JPL
(307463) 2002 VU13039.331.214.05.47±0.83252.9+33.6
−31.3
0.160.179+0.202
−0.103
2002Marc W. BuieJPL
(84719) 2002 VR12839.328.914.05.58±0.37448.5+42.1
−43.2
10.052+0.027
−0.018
0.60±0.022002NEATJPL
(55638) 2002 VE9539.430.416.35.70±0.06249.8+13.5
−13.1
0.150.149+0.019
−0.016
0.72±0.052002NEATJPL

References

  1. Malhotra, Renu (1995). "The Origin of Pluto's Orbit: Implications for the Solar System Beyond Neptune". Astronomical Journal. 110: 420. arXiv:astro-ph/9504036. Bibcode:1995AJ....110..420M. doi:10.1086/117532. S2CID 10622344.
  2. Almeida, A.J.C; Peixinho, N.; Correia, A.C.M. (December 2009). "Neptune Trojans & Plutinos: Colors, sizes, dynamics, & their possible collisions". Astronomy & Astrophysics. 508 (2): 1021–1030. arXiv:0910.0865. doi:10.1051/0004-6361/200911943. S2CID 53772214. Retrieved 2019-07-20.
  3. Lewis, John S. (2004). Physics & Chemistry of the Solar System. Centaurs & Trans-Neptunian Objects. Academic Press. pp. 409–412. ISBN 012446744X. Retrieved 2019-07-21.
  4. Wan, X.-S; Huang, T.-Y. (2001). "The orbit evolution of 32 plutinos over 100 million year". Astronomy and Astrophysics. 368 (2): 700–705. Bibcode:2001A&A...368..700W. doi:10.1051/0004-6361:20010056.
  5. Yu, Qingjuan; Tremaine, Scott (1999). "The Dynamics of Plutinos". Astronomical Journal. 118 (4): 1873–1881. arXiv:astro-ph/9904424. Bibcode:1999AJ....118.1873Y. doi:10.1086/301045. S2CID 14482507.
  • 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)
  • 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.
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