User:Kepler-1229b/sandbox/pdpold

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Tancredi's assessment[edit]

In 2010, Gonzalo Tancredi presented a report to the IAU evaluating a list of 46 candidates for dwarf planet status based on light-curve-amplitude analysis and a calculation that the object was more than 450 kilometres (280 mi) in diameter. Some diameters were measured, some were best-fit estimates, and others used an assumed albedo of 0.10 to calculate the diameter. Of these, he identified 15 as dwarf planets by his criteria (including the 4 accepted by the IAU), with another 9 being considered possible. To be cautious, he advised the IAU to "officially" accept as dwarf planets the top three not yet accepted: Sedna, Orcus, and Quaoar.[1] Although the IAU had anticipated Tancredi's recommendations, a decade later the IAU had never responded.

Brown's assessment[edit]

EarthMoonCharonCharonNixNixKerberosKerberosStyxStyxHydraHydraPlutoPlutoDysnomiaDysnomiaErisErisNamakaNamakaHi'iakaHi'iakaHaumeaHaumeaMakemakeMakemakeMK2MK2XiangliuXiangliuGonggongGonggongWeywotWeywotQuaoarQuaoarSednaSednaVanthVanthOrcusOrcusActaeaActaeaSalaciaSalacia2002 MS42002 MS4File:10 Largest Trans-Neptunian objects (TNOS).png
Artistic comparison of Pluto, Eris, Makemake, Haumea, Gonggong (2007 OR10), Sedna, Quaoar, Orcus, 2002 MS4, and Salacia.
Brown's categories Min. ⌀ Number of objects
nearly certainly >900 km 10
highly likely 600–900 km 17 (27 total)
likely 500–600 km 41 (68 total)
probably 400–500 km 62 (130 total)
possibly 200–400 km 611 (741 total)
Source: Mike Brown,[2] as of 2020 October 22

Mike Brown considers 130 trans-Neptunian bodies to be "probably" dwarf planets, ranked them by estimated size.[2] He does not consider asteroids, stating "in the asteroid belt Ceres, with a diameter of 900 km, is the only object large enough to be round."[2]

The terms for varying degrees of likelihood he split these into:

  • Near certainty: diameter estimated/measured to be over 900 kilometres (560 mi). Sufficient confidence to say these must be in hydrostatic equilibrium, even if predominantly rocky. 10 objects as of 2020.
  • Highly likely: diameter estimated/measured to be over 600 kilometres (370 mi). The size would have to be "grossly in error" or they would have to be primarily rocky to not be dwarf planets. 17 objects as of 2020.
  • Likely: diameter estimated/measured to be over 500 kilometres (310 mi). Uncertainties in measurement mean that some of these will be significantly smaller and thus doubtful. 41 objects as of 2020.
  • Probably: diameter estimated/measured to be over 400 kilometres (250 mi). Expected to be dwarf planets, if they are icy, and that figure is correct. 62 objects as of 2020.
  • Possibly: diameter estimated/measured to be over 200 kilometres (120 mi). Icy moons transition from a round to irregular shape in the 200–400 km range, suggesting that the same figure holds true for KBOs. Thus, some of these objects could be dwarf planets. 611 objects as of 2020.
  • Probably not: diameter estimated/measured to be under 200 km. No icy moon under 200 km is round, and the same may be true of KBOs. The estimated size of these objects would have to be in error for them to be dwarf planets.

Beside the five accepted by the IAU, the 'nearly certain' category includes Gonggong, Quaoar, Sedna, Orcus, 2002 MS4 and Salacia.

Grundy et al.’s assessment[edit]

Grundy et al. propose that dark, low-density TNOs in the size range of approximately 400–1000 km are transitional between smaller, porous (and thus low-density) bodies and larger, denser, brighter and geologically differentiated planetary bodies (such as dwarf planets). Bodies in this size range should have begun to collapse the interstitial spaces left over from their formation, but not fully, leaving some residual porosity.[3]

Many TNOs in the size range of about 400–1000 km have oddly low densities, in the range of about 1.0–1.2 g/cm3, that are substantially less than dwarf planets such as Pluto, Eris and Ceres, which have densities closer to 2. Brown has suggested that large low-density bodies must be composed almost entirely of water ice, since he presumed that bodies of this size would necessarily be solid. However, this leaves unexplained why TNOs both larger than 1000 km and smaller than 400 km, and indeed comets, are composed of a substantial fraction of rock, leaving only this size range to be primarily icy. Experiments with water ice at the relevant pressures and temperatures suggest that substantial porosity could remain in this size range, and it is possible that adding rock to the mix would further increase resistance to collapsing into a solid body. Bodies with internal porosity remaining from their formation could be at best only partially differentiated, in their deep interiors. (If a body had begun to collapse into a solid body, there should be evidence in the form of fault systems from when its surface contracted.) The higher albedos of larger bodies is also evidence of full differentiation, as such bodies were presumably resurfaced with ice from their interiors. Grundy et al.[3] propose therefore that mid-size (< 1000 km), low-density (< 1.4 g/ml) and low-albedo (< ~0.2) bodies such as Salacia, Varda, Gǃkúnǁʼhòmdímà and (55637) 2002 UX25 are not differentiated planetary bodies like Orcus, Quaoar and Charon. The boundary between the two populations would appear to be in the range of about 900–1000 km.[3]

If Grundy et al.[3] are correct, then among known bodies in the outer Solar System only Pluto–Charon, Eris, Haumea, Gonggong, Makemake, Quaoar, Orcus, Sedna and perhaps Salacia (which if it were spherical and had the same albedo as its moon would have a density of between 1.4 and 1.6 g/cm3, calculated a few months after Grundy et al.'s initial assessment, though still an albedo of only 0.04)[4] are likely to have compacted into fully solid bodies, and thus to possibly have become dwarf planets at some point in their past or to still be dwarf planets at present.

Likeliest dwarf planets[edit]

The assessments of the IAU, Tancredi et al., Brown and Grundy et al. for sixteen of the largest potential dwarf planets are as follows. For the IAU, the acceptance criteria were for naming purposes. Several of these objects had not yet been discovered when Tancredi et al. did their analysis. Brown's sole criterion is diameter; he accepts a great many more as highly likely to be dwarf planets (see below). Grundy et al. did not determine which bodies were dwarf planets, but rather which could not be. A red No marks objects too dark or not dense enough to be solid bodies, a question mark the smaller bodies consistent with being differentiated (the question of current equilibrium was not addressed).

Mercury, Iapetus, Earth's moon and Phoebe are included for comparison, as none of these objects are in equilibrium today. The first three of these objects are round at present, but Phoebe is not. Triton (which formed as a TNO and is likely still in equilibrium) and Charon are included as well.

Designation Measured mean
diameter (km) 		Density
(g/cm3) 		Albedo Per Grundy
et al.[3][4] 		Per Brown[2] Per Tancredi
et al.[1] 		Per IAU Category
No Mercury 4880 5.427 0.142 (no longer in equilibrium)[5] (planet)
No The Moon 3475 3.344 0.136 (no longer in equilibrium)[6][7] (moon of Earth)
N I Triton 2707±2 2.06 0.76 (likely in equilibrium)[8] (moon of Neptune)
134340 Pluto 2376±3 1.854±0.006 0.49 to 0.66 Yes Yes Yes Yes 2:3 resonant
136199 Eris 2326±12 2.43±0.05 0.96 Yes Yes Yes Yes SDO
136108 Haumea ≈ 1560 ≈ 2.018 0.51 Yes Yes Yes Yes
(naming rules)		 cubewano
No S VIII Iapetus 1469±6 1.09±0.01 0.05 to 0.5 (no longer in equilibrium)[9] (moon of Saturn)
136472 Makemake 1430+38
−22		 1.9±0.2 0.81 Yes Yes Yes Yes
(naming rules)		 cubewano
225088 Gonggong 1230±50 1.74±0.16 0.14 Yes Yes NA 3:10 resonant
P I Charon 1212±1 1.70±0.02 0.2 to 0.5 (possibly in equilibrium)[10] (moon of Pluto)
50000 Quaoar 1110±5 2.0±0.5 0.11 Yes Yes Yes cubewano
90377 Sedna 995±80 ? 0.32 Yes Yes Yes detached
1 Ceres 946±2 2.16±0.01 0.09 (close to equilibrium)[11] Yes asteroid
90482 Orcus 910+50
−40		 1.53±0.14 0.23 Yes Yes Yes 2:3 resonant
120347 Salacia 846±21 1.5±0.12 0.04 Maybe Yes Maybe cubewano
(307261) 2002 MS4 778±11 ? 0.10 No Yes NA cubewano
(55565) 2002 AW197 768±39 ? 0.11 No Maybe Yes cubewano
174567 Varda 749±18 1.27±0.06 0.10 No Maybe Maybe 4:7 resonant
(532037) 2013 FY27 742+78
−83		 ? 0.17 No Maybe NA SDO
28978 Ixion 710±0.2 ? 0.10 No Maybe Yes 2:3 resonant
(208996) 2003 AZ84 707±24 ? 1.1±0.2 0.10 No Maybe Yes 2:3 resonant
No S IX Phoebe 213±2 1.64±0.03 0.06 (no longer in equilibrium)[12] (moon of Saturn)

Largest candidates[edit]

The following trans-Neptunian objects have estimated diameters at least 400 kilometres (250 mi) and so were considered "probable" dwarf planets in Brown's early assessment. Not all bodies estimated to be this size are included. The list is complicated by bodies such as 47171 Lempo that were at first assumed to be large single objects but later discovered to be binary or triple systems of smaller bodies.[13] The dwarf planet Ceres is included, but not other asteroids. Explanations and sources for the measured masses and diameters can be found in the corresponding articles linked in column "Designation" of the table.

The Best diameter column uses a measured diameter if one exists, otherwise it uses Brown's assumed-albedo diameter. If Brown does not list the body, the size is calculated from an assumed-albedo of 9% per Johnston.[14]

Designation Best[a]
diameter
km 		Measured per
measured 		Category
Mass[b]
(1018 kg) 		H

[15][16]

Diameter
(km) 		Method Geometric
albedo[c]
(%)
134340 Pluto 2377 13030 −0.76 2377±3 direct 63 2:3 resonant
136199 Eris 2326 16466 −1.17 2326±12 occultation 96 SDO
136108 Haumea 1559 4006 0.43 1559 occultation 49 cubewano
136472 Makemake 1429 3100 0.05 1429+38
−20 		occultation 83 cubewano
225088 Gonggong 1230 1750 2.34 1230±50 thermal 14 3:10 resonant
50000 Quaoar 1103 1400 2.74 1103+47
−33 		occultation 11 cubewano
1 Ceres 939 939 3.36 939±2 direct 9 asteroid belt
90482 Orcus 910 641 2.31 910+50
−40 		thermal 25 2:3 resonant
90377 Sedna 906 1.83 906+314
−258 		thermal 40 detached
120347 Salacia 846 492 4.27 846±21 thermal 5 cubewano
(307261) 2002 MS4 800 3.5 800±24 occultation < 11 cubewano
(55565) 2002 AW197 768 3.57 768+39
−38 		thermal 11 cubewano
174567 Varda 749 245 3.61 749±18 occultation 11 cubewano
(532037) 2013 FY27 742 3.15 742+78
−83 		thermal 18 SDO
28978 Ixion 710 3.83 710±0.2 occultation 10 2:3 resonant
(208996) 2003 AZ84 707 3.74 707±24 occultation 11 2:3 resonant
(90568) 2004 GV9 680 4.23 680±34 thermal 8 cubewano
(145452) 2005 RN43 679 3.89 679+55
−73 		thermal 11 cubewano
(55637) 2002 UX25 659 125 3.87 659±38 thermal 12 cubewano
2018 VG18 656 3.6 SDO
229762 Gǃkúnǁʼhòmdímà 655 136 3.69 655+14
−13 		occultation 14 SDO
20000 Varuna 654 3.76 654+154
−102 		thermal 12 cubewano
2018 AG37 645 4.19 SDO
2014 UZ224 635 3.4 635+65
−72 		thermal 14 SDO
(523794) 2015 RR245 626 3.8 SDO
(523692) 2014 EZ51 626 3.8 detached
2010 RF43 611 3.9 SDO
19521 Chaos 600 4.8 600+140
−130 		thermal 5 cubewano
2010 JO179 600–900 4 SDO
2012 VP113 300–1000 4 detached
2010 KZ39 597 4 detached
(303775) 2005 QU182 584 3.8 584+155
−144 		thermal 13 cubewano
(543354) 2014 AN55 583 4.1 SDO
2015 KH162 583 4.1 detached
(78799) 2002 XW93 565 5.5 565+71
−73 		thermal 4 SDO
2006 QH181 556 4.3 SDO
2002 XV93 549 5.42 549+22
−23 		thermal 4 2:3 resonant
(84922) 2003 VS2 548 4.1 548+30
−45 		occultation 15 2:3 resonant
(523639) 2010 RE64 543 4.4 SDO
(523759) 2014 WK509 543 4.4 detached
(528381) 2008 ST291 543 4.4 detached
(470443) 2007 XV50 543 4.4 cubewano
(482824) 2013 XC26 543 4.4 cubewano
(523671) 2013 FZ27 543 4.4 1:2 resonant
2004 XR190 538 4.3 538 occultation 12 detached
2015 BP519 530 4.5 SDO
(278361) 2007 JJ43 530 4.5 cubewano
(470308) 2007 JH43 530 4.5 2:3 resonant
2014 WP509 530 4.5 cubewano
(145451) 2005 RM43 524 4.4 524+96
−103 		thermal 11 SDO
2013 AT183 518 4.6 SDO
2014 FC69 518 4.6 detached
(499514) 2010 OO127 518 4.6 cubewano
2014 YA50 518 4.6 cubewano
2017 OF69 518 4.6 2:3 resonant
2020 FY30 517 4.67 SDO
(84522) 2002 TC302 514 3.9 514±15 occultation 14 2:5 resonant
(120348) 2004 TY364 512 4.52 512+37
−40 		thermal 10 2:3 resonant
(145480) 2005 TB190 507 4.4 507+127
−116 		thermal 15 detached
(470599) 2008 OG19 506 4.7 SDO
2014 FC72 506 4.7 detached
2014 HA200 506 4.7 SDO
(315530) 2008 AP129 506 4.7 cubewano
(472271) 2014 UM33 506 4.7 cubewano
(523681) 2014 BV64 506 4.7 cubewano
2010 FX86 506 4.7 cubewano
2015 BZ518 506 4.7 cubewano
(202421) 2005 UQ513 498 3.6 498+63
−75 		thermal 26 cubewano
(523742) 2014 TZ85 494 4.8 4:7 resonant
(523635) 2010 DN93 490 4.8 detached
2003 QX113 490 5.1 SDO
2003 UA414 490 5 SDO
(523693) 2014 FT71 490 5 4:7 resonant
2014 HZ199 479 5 cubewano
2014 BZ57 479 5 cubewano
(523752) 2014 VU37 479 5.1 cubewano
(495603) 2015 AM281 479 4.8 detached
(455502) 2003 UZ413 472 4.38 472+122
−25 		thermal 15 2:3 resonant
(523645) 2010 VK201 471 5 cubewano
2015 AJ281 468 5 4:7 resonant
(523757) 2014 WH509 468 5.2 cubewano
2014 JP80 468 5 2:3 resonant
2014 JR80 468 5.1 2:3 resonant
(523750) 2014 US224 468 5 cubewano
2013 FS28 468 4.9 SDO
2010 RF188 468 5.2 SDO
2011 WJ157 468 5 SDO
(120132) 2003 FY128 460 4.6 460±21 thermal 12 SDO
2010 ER65 457 5.2 detached
(445473) 2010 VZ98 457 4.8 SDO
2010 RF64 457 5.7 cubewano
(523640) 2010 RO64 457 5.2 cubewano
2010 TJ 457 5.7 SDO
2014 OJ394 457 5.1 detached
2014 QW441 457 5.2 cubewano
2014 AM55 457 5.2 cubewano
(523772) 2014 XR40 457 5.2 cubewano
(523653) 2011 OA60 457 5.1 cubewano
(26181) 1996 GQ21 456 4.9 456+89
−105 		thermal 6 SDO
(84719) 2002 VR128 449 5.58 449+42
−43 		thermal 5 2:3 resonant
2013 SF106 451 4.96 SDO
2012 VB116 449 5.2 cubewano
(471137) 2010 ET65 447 5.1 SDO
(471165) 2010 HE79 447 5.1 2:3 resonant
2010 EL139 447 5.6 2:3 resonant
(523773) 2014 XS40 447 5.4 cubewano
2014 XY40 447 5.1 cubewano
2015 AH281 447 5.1 cubewano
2014 CO23 447 5.3 cubewano
(523690) 2014 DN143 447 5.3 cubewano
(523738) 2014 SH349 447 5.4 cubewano
2014 FY71 447 5.4 4:7 resonant
(471288) 2011 GM27 447 5.1 cubewano
(532093) 2013 HV156 447 5.2 1:2 resonant
471143 Dziewanna 433 3.8 433+63
−64 		thermal 30 SDO
(444030) 2004 NT33 423 4.8 423+87
−80 		thermal 12 4:7 resonant
(182934) 2002 GJ32 416 6.16 416+81
−73 		thermal 3 SDO
(469372) 2001 QF298 408 5.43 408+40
−45 		thermal 7 2:3 resonant
(175113) 2004 PF115 406 4.54 406+98
−85 		thermal 12 2:3 resonant
38628 Huya 406 5.04 406±16 thermal 10 2:3 resonant
(307616) 2003 QW90 401 5 401+63
−48 		thermal 8 cubewano
(469615) 2004 PT107 400 6.33 400+45
−51 		thermal 3 cubewano
  1. ^ a b Cite error: The named reference tancredi-2010 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference brown-list was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Grundy2019 was invoked but never defined (see the help page).
  4. ^ a b Grundy, W.M.; Noll, K.S.; Roe, H.G.; Buie, M.W.; Porter, S.B.; Parker, A.H.; et al. (December 2019). "Mutual orbit orientations of transneptunian binaries" (PDF). Icarus. 334: 62–78. Bibcode:2019Icar..334...62G. doi:10.1016/j.icarus.2019.03.035. S2CID 133585837. Archived from the original (PDF) on 7 April 2019.
  5. ^ Sean Solomon, Larry Nittler & Brian Anderson, eds. (2018) Mercury: The View after MESSENGER. Cambridge Planetary Science series no. 21, Cambridge University Press. Chapter 3.
  6. ^ Matsuyama, Isamu (January 2013). "Fossil figure contribution to the lunar figure". Icarus. 222 (1): 411–414. Bibcode:2013Icar..222..411M. doi:10.1016/j.icarus.2012.10.025.
  7. ^ Bursa, M. (October 1984). "Secular Love Numbers and Hydrostatic Equilibrium of Planets". Earth, Moon, and Planets. 31 (2): 135–140. Bibcode:1984EM&P...31..135B. doi:10.1007/BF00055525. S2CID 119815730.
  8. ^ Thomas, P.C. (December 2000). "The Shape of Triton from Limb Profiles". Icarus. 148 (2): 587–588. Bibcode:2000Icar..148..587T. doi:10.1006/icar.2000.6511.
  9. ^ Thomas, P.C. (July 2010). "Sizes, shapes, and derived properties of the saturnian satellites after the Cassini nominal mission" (PDF). Icarus. 208 (1): 395–401. Bibcode:2010Icar..208..395T. doi:10.1016/j.icarus.2010.01.025.
  10. ^ Kholshevnikovab, K.V.; Borukhaa, M.A.; Eskina, B.B.; Mikryukov, D.V. (23 October 2019). "On the asphericity of the figures of Pluto and Charon". Icarus. 181: 104777. doi:10.1016/j.pss.2019.104777. S2CID 209958465.
  11. ^ Raymond, C.; Castillo-Rogez, J.C.; Park, R.S.; Ermakov, A.; et al. (September 2018). "Dawn Data Reveal Ceres' Complex Crustal Evolution" (PDF). European Planetary Science Congress. Vol. 12.
  12. ^ Jia-Rui C. Cook; Dwayne Brown (26 April 2012). "Cassini Finds Saturn Moon Has Planet-Like Qualities". JPL/NASA. Archived from the original on 27 April 2012.
  13. ^ "AstDys (47171) 1999TC36 Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 2009-12-07.
  14. ^ Johnston, Wm. Robert (24 May 2019). "List of Known Trans-Neptunian Objects". Johnston's Archive. Retrieved 11 August 2019.
  15. ^ Cite error: The named reference mpc-tno was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference mpc-sdo was invoked but never defined (see the help page).


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