Plutino

{{Short description|In astronomy, a dynamical group of trans-Neptunian objects}}

{{about-distinguish-text|the dynamical group|plutoids or plutons}}

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 {{dp|Orcus}}, {{mpl|208996|2003 AZ|84}}, and {{dp|Ixion}}. 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

Image:ThePlutinos Size Albedo Color2.svg 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.{{cite journal |last1=Malhotra |title=The Origin of Pluto's Orbit: Implications for the Solar System Beyond Neptune |journal=Astronomical Journal |volume=110 |year=1995 |page=420 |arxiv = astro-ph/9504036 |bibcode = 1995AJ....110..420M |doi = 10.1086/117532 |first1= Renu|s2cid= 10622344}} The 3:2 resonance is a low-order resonance and is thus the strongest and most stable among all resonances.{{cite journal|last1=Almeida|first1=A.J.C|last2=Peixinho|first2=N.|last3=Correia|first3=A.C.M. |url=https://www.researchgate.net/publication/45876510|title=Neptune Trojans & Plutinos: Colors, sizes, dynamics, & their possible collisions|date=December 2009|journal=Astronomy & Astrophysics|doi=10.1051/0004-6361/200911943|volume=508|issue=2|pages=1021–1030|access-date=2019-07-20|arxiv=0910.0865|s2cid=53772214}} 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.{{cite book|url=https://books.google.com/books?id=QpcKesJwp28C&pg=PA411|first=John S.|publisher=Academic Press|department=Centaurs & Trans-Neptunian Objects|last=Lewis|isbn=012446744X |title=Physics & Chemistry of the Solar System|date=2004|pages=409–412|access-date=2019-07-21}}

= Orbital characteristics =

File:Plutino distributions and sizes.png

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, which follows the most highly inclined orbit (34.5°)
{{mpl|(15875) 1996 TP|66}}, which has the most elliptical orbit (its eccentricity is 0.33), with the perihelion halfway between Uranus and Neptune
{{mpl|(470308) 2007 JH|43}} following a quasi-circular orbit
List of unnumbered trans-Neptunian objects: 2002#2002 VX130 lying almost perfectly on the ecliptic (inclination less than 1.5°)
15810 Arawn, a quasi-satellite of Pluto{{cite journal |title=The analemma criterion: accidental quasi-satellites are indeed true quasi-satellites |first1=Carlos |last1=de la Fuente Marcos |last2=de la Fuente Marcos |first2=Raúl |journal=Monthly Notices of the Royal Astronomical Society |date=2016 |volume=462 |issue=3 |pages=3344–3349 |arxiv=1607.06686 |doi=10.1093/mnras/stw1833 |doi-access=free |bibcode=2016MNRAS.462.3344D}}

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.{{cite journal

| author=Wan, X.-S

|author2=Huang, T.-Y.

| title=The orbit evolution of 32 plutinos over 100 million year

| journal=Astronomy and Astrophysics

| volume=368

| issue=2 | pages=700–705 | year=2001

| bibcode=2001A&A...368..700W| doi = 10.1051/0004-6361:20010056

| doi-access=free}} 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.{{cite journal |first1=Qingjuan |last1=Yu |first2=Scott |last2=Tremaine |title=The Dynamics of Plutinos |journal=Astronomical Journal |volume=118 |year=1999 |issue= 4|pages=1873–1881 |arxiv = astro-ph/9904424 |bibcode = 1999AJ....118.1873Y |doi = 10.1086/301045 |s2cid=14482507 }}

Orbital diagrams

File: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.

File:TheKuiperBelt 60AU LargePlutinos.svg|Orbits and sizes of the larger plutinos (and the reference non-plutino {{mpl-|119951|2002 KX|14}}). Orbital eccentricity is represented by segments extending horizontally from perihelion to aphelion; inclination is shown on the vertical axis.

File:TheKuiperBelt 60AU Plutinos distribution.svg|The distribution of plutinos (and the reference non-plutino {{mp|2002 KX|14}}). Small inserts show histograms for the distributions of orbital inclination and eccentricity.

Brightest objects

The plutinos brighter than H_V=6 include:

class="wikitable sortable" style="width:100%; text-align:center; font-size: 0.9em;" ! 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	data-sort-value="-0.7"\|−0.7	2322	130	0.49–0.66		1930	Clyde Tombaugh	{{JPL\|134340}}
90482 Orcus	39.2	30.3	20.6	data-sort-value="2.3"\|{{val\|2.31\|0.03}}	data-sort-value="917"\|{{val\|917\|25}}	{{val\|6.32\|0.05}}	{{val\|0.28\|0.06}}	0.37	2004	M. Brown, C. Trujillo, D. Rabinowitz	{{JPL\|90482}}
{{mpl\|(208996) 2003 AZ\|84}}	39.4	32.3	13.6	data-sort-value="3.7"\|{{val\|3.74\|0.08}}	data-sort-value="717"\|{{val\|727.0\|+61.9
66.5}}	≈ 3	{{val\|0.107\|+0.023
0.016}}	{{val\|0.38\|0.04}}	2003	M. Brown, C. Trujillo	{{JPL\|208996}}
28978 Ixion	39.7	30.1	19.6	data-sort-value="3.8"\|{{val\|3.828\|0.039}}	data-sort-value="617"\|{{val\|617\|19\|20}}	≈ 3	{{val\|0.141\|0.011}}	0.61	2001	Deep Ecliptic Survey	{{JPL\|28978}}
{{mpl\|(678191) 2017 OF\|69}}	39.5	31.3	13.6	data-sort-value="4.09"\|{{val\|4.091\|0.12}}	data-sort-value="530"\|≈ 380–680	?	?	?	2017	D. J. Tholen, S. S. Sheppard, C. Trujillo	{{JPL\|2017+OF69}}
{{mpl\|(84922) 2003 VS\|2}}	39.3	36.4	14.8	data-sort-value="4.1"\|{{val\|4.1\|0.38}}	data-sort-value="523"\|{{val\|523.0\|+35.1
34.4}}	≈ 1.5	{{val\|0.147\|+.063
.043}}	{{val\|0.59\|0.02}}	2003	NEAT	{{JPL\|84922}}
{{mpl\|(455502) 2003 UZ\|413}}	39.2	30.4	12.0	data-sort-value="4.4"\|{{val\|4.38\|0.05}}	data-sort-value="600"\|≈ 600	≈ 2	?	{{val\|0.46\|0.06}}	2001	M. Brown, C. Trujillo, D. Rabinowitz	{{JPL\|455502}}
{{mpl\|(556068) 2014 JR\|80}}	39.5	36.0	15.4	data-sort-value="4.9"\|{{val\|4.9}}	data-sort-value="405"\|≈ 240–670	?	?	?	2014	Pan-STARRS	{{JPL\|2014+JR80}}
{{mpl\|(578993) 2014 JP\|80}}	39.5	36.7	19.4	data-sort-value="4.9"\|{{val\|4.9}}	data-sort-value="455"\|≈ 240–670	?	?	?	2014	Pan-STARRS	{{JPL\|2014+JP80}}
38628 Huya	39.4	28.5	15.5	data-sort-value="5.0"\|{{val\|5.04\|0.03}}	data-sort-value="406"\|{{val\|406\|16}}	≈ 0.5	{{val\|0.083\|0.004}}	{{val\|0.57\|0.09}}	2000	Ignacio Ferrin	{{JPL\|38628}}
{{mpl\|(469987) 2006 HJ\|123}}	39.3	27.4	12.0	data-sort-value="5.3"\|{{val\|5.32\|0.66}}	data-sort-value="283"\|{{val\|283.1\|+142.3
110.8}}	≈ 0.012	{{val\|0.136\|+0.308
0.089}}		2006	Marc W. Buie	{{JPL\|469987}}
{{mpl\|(612533) 2002 XV\|93}}	39.3	34.5	13.3	data-sort-value="5.4"\|{{val\|5.42\|0.46}}	data-sort-value="549"\|{{val\|549.2\|+21.7
23.0}}	≈ 1.7	{{val\|0.040\|+0.020
0.015}}	{{val\|0.37\|0.02}}	2001	M.W.Buie	{{JPL\|2002+XV93}}
{{mpl\|(469372) 2001 QF\|298}}	39.3	34.9	22.4	data-sort-value="5.4"\|{{val\|5.43\|0.07}}	data-sort-value="408"\|{{val\|408.2\|+40.2
44.9}}	≈ 0.7	{{val\|0.071\|+0.020
0.014}}	{{val\|0.39\|0.06}}	2001	Marc W. Buie	{{JPL\|469372}}
47171 Lempo	39.3	30.6	8.4	data-sort-value="5.4"\|{{val\|5.41\|0.10}}	data-sort-value="393"\|{{val\|393.1\|+25.2
26.8}} (triple)	{{val\|0.1275\|0.0006}}	{{val\|0.079\|+0.013
0.011}}	{{val\|0.70\|0.03}}	1999	E. P. Rubenstein, L.-G. Strolger	{{JPL\|47171}}
{{mpl\|(307463) 2002 VU\|130}}	39.3	31.2	14.0	data-sort-value="5.5"\|{{val\|5.47\|0.83}}	data-sort-value="253"\|{{val\|252.9\|+33.6
31.3}}	≈ 0.16	{{val\|0.179\|+0.202
0.103}}		2002	Marc W. Buie	{{JPL\|307463}}
{{mpl\|(84719) 2002 VR\|128}}	39.3	28.9	14.0	data-sort-value="5.6"\|{{val\|5.58\|0.37}}	data-sort-value="448"\|{{val\|448.5\|+42.1
43.2}}	≈ 1	{{val\|0.052\|+0.027
0.018}}	{{val\|0.60\|0.02}}	2002	NEAT	{{JPL\|84719}}
{{mpl\|(55638) 2002 VE\|95}}	39.4	30.4	16.3	data-sort-value="5.7"\|{{val\|5.70\|0.06}}	data-sort-value="250"\|{{val\|249.8\|+13.5
13.1}}	≈ 0.15	{{val\|0.149\|+0.019
0.016}}	{{val\|0.72\|0.05}}	2002	NEAT	{{JPL\|55638}}

(link to all of the orbits of these objects listed above are [https://www.spacereference.org/solar-system#ob=90482-orcus-2004-dw,455502-2003-uz413,469987-2006-hj123,55638-2002-ve95,84719-2002-vr128,84922-2003-vs2,208996-2003-az84,307463-2002-vu130,469372-2001-qf298,612533-2002-xv93,578993-2014-jp80,556068-2014-jr80,2017-of69,28978-ixion-2001-kx76,38628-huya-2000-eb173,47171-lempo-1999-tc36,134340-pluto-1930-bm here])

References

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). [https://web.archive.org/web/20060525051103/http://www.ifa.hawaii.edu/faculty/jewitt/papers/2006/DJ06.pdf 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. [https://arxiv.org/abs/astro-ph/0308467 preprint on arXiv]
Minor Planet Center Orbit database (MPCORB) as of 2008-10-05.
Minor Planet Circular 2008-S05 (October 2008) [http://www.minorplanetcenter.org/mpec/K08/K08S05.html Distant Minor planets] was used for orbit classification.

External links

[http://www2.ess.ucla.edu/~jewitt/kb/plutino.html David Jewitt on Plutinos]
[http://www.minorplanetcenter.org/iau/lists/TNOs.html Minor Planet Center, List of TNOs]
[http://www.minorplanetcenter.org/mpec/K06/K06D28.html MPC List of Distant Minor Planets]

Category:Solar System