List of possible dwarf planets

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Illustration of the relative sizes, albedos, and colours of the largest trans-Neptunian objects

It is estimated that there may be 200 dwarf planets in the Kuiper belt of the outer Solar System and up to 10,000 in the region beyond.[1][2] The International Astronomical Union (IAU) has accepted four of these: Pluto, Eris, Haumea, and Makemake, as well as Ceres in the inner Solar System. This article lists these and the more likely of the remaining known possibilities.

IAU naming procedures[edit]

In 2008, the IAU modified its naming procedures such that objects considered most likely to be dwarf planets receive differing treatment than others. Objects that have an absolute magnitude (H) less than +1 (and hence a minimum diameter of 838 kilometres (521 mi) if the albedo is below 100%[3]) are overseen by two naming committees, one for minor planets and one for planets. Once named, the objects are declared to be dwarf planets. Makemake and Haumea are the only objects to have proceeded through the naming process as presumed dwarf planets; currently there are no other bodies that meet this criterion. All other bodies are named by the minor-planet naming committee alone, and the IAU has not stated how or if they will be accepted as dwarf planets.

Limiting values[edit]

Calculation of the diameter of Ixion depends on the albedo (the fraction of light that it reflects), which is currently unknown.

The qualifying feature of a dwarf planet is that it "has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape".[4][5][6] Except for Pluto and Ceres,[citation needed] current observations are insufficient for a direct determination as to whether a body meets this definition. However, Michael Brown estimates that an icy body relaxes into hydrostatic equilibrium at a diameter somewhere between 200 and 400 km.[1] Thus, all the trans-Neptunian objects (TNOs) listed below are estimated to be at least 300 kilometres (190 mi) in diameter, though not all bodies estimated to be that size are included. The lists are further complicated by bodies such as (47171) 1999 TC36 that were at first assumed to be large single objects but were later discovered to be smaller binary or triple systems.[7]

Ceres is the only identified dwarf planet in the asteroid belt. 4 Vesta, the second-most-massive asteroid, appears to have a fully differentiated interior and was therefore in equilibrium at some point in its history, but it is not today.[8] The third-most massive object, 2 Pallas, has a somewhat irregular surface and is thought to have only a partially differentiated interior. Brown estimates that, because rocky objects are more rigid than icy objects, rocky objects below 900 kilometres (560 mi) in diameter may not be in hydrostatic equilibrium and thus not dwarf planets.[1]

Last, a dwarf planet may not be the satellite (moon) of another body, even though several of them are larger than the recognized dwarf planets.

Probable per Brown[edit]

Mike Brown considers a large number of trans-Neptunian bodies, ranked by estimated size, to be "probably" dwarf planets.[9] He did not consider asteroids, stating "In the asteroid belt Ceres, with a diameter of 900 km, is the only object large enough to be round".[9]

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.
  • 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.
  • 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.
  • Probable: diameter estimated/measured to be over 400 kilometres (250 mi). Expected to be dwarf planets, if they are icy, and that figure is correct.
  • Possible: 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.
  • Probably not: diameter estimated/measured to be under 200 km. No icy moon under 200 km is round, suggesting that the same is true for KBOs. The estimated size of these objects would have to be in error for them to be dwarf planets.

Probable per Tancredi[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 the assumption that the object was more than 450 kilometres (280 mi) in diameter. Some diameters are measured, some are best-fit estimates, and others use an assumed albedo of 0.10. Of these, he identified 15 as dwarf planets by his criteria, with another nine being considered possible. To be cautious, he advised the IAU to "officially" accept as dwarf planets the top three: Sedna, Orcus, and Quaoar.[10] Although the IAU had anticipated Tancredi's recommendations, as of 2013, they had not responded.

Likeliest possible dwarf planets[edit]

Brown's categories Min. Number of objects
near certainty 900 km 10
highly likely 600 km 22
likely 500 km 44
probably 400 km 75
possibly 200 km 359
Source: Mike Brown,[9] January 20, 2015

This is a list of the minor planets with an estimated diameter of greater than 300 km and that may be dwarf planets. All are trans-Neptunian objects, except Ceres.

The default sort is per Brown's size estimate. The IAU-recognised dwarf planets have bold names. Brown's diameter estimates are in red when they are based upon an assumed albedo. Explanations and sources for the measured masses and diameters can be found in the corresponding articles linked in column "Body" of the table.

Body Per Brown[9] Measured per
measured
Diameter
per assumed albedo
Result
per Tancredi[10]
Category Best[a]
Diameter
km
H
Diameter[b]
(km)
Albedo
%
Mass
(Zg)
H
[11][12]
Diameter
(km)
Albedo[c]
%
Small
albedo=100%
(km)
Large
albedo=4%
(km)
Eris −1.1 2330 99 16700 −1.2 2326 99 2310 11548 accepted (measured) SDO 2326
Pluto −0.7 2329 64 13100 −0.8 2368 66 1921 9605 accepted (measured) 2:3 resonant 2368
Makemake 0.1 1426 81 −0.4 1430 125 1598 7989 accepted cubewano 1430
(225088) 2007 OR10 2 1290 19 2 1280 17 529 2645 SDO 1280
Haumea 0.4 1252 80 4000 0.1 1430 79 1269 6346 accepted cubewano 1430
Quaoar 2.7 1092 13 1400 2.4 1074 17 440 2200 accepted (and recommended) cubewano 1074
Sedna 1.8 1041 32 1.5 995 45 666 3330 accepted (and recommended) detached 995
Orcus 2.3 983 23 580 2.2 917 28 483 2413 accepted (and recommended) 2:3 resonant 917
(307261) 2002 MS4 4 960 5 3.7 934 7 242 1209 cubewano 934
Ceres 943 3.3 952 9 291 1454 main belt 952
Salacia 4.2 921 4 450 4.2 854 5 192 960 possible cubewano 854
(208996) 2003 AZ84 3.7 747 11 3.8 727 10 231 1155 accepted 2:3 resonant 727
2013 FY27 3.5 735 14 3 334 1669 SDO 735
Varuna 4 722 9 3.6 668 14 253 1266 accepted cubewano 668
(55637) 2002 UX25 3.9 704 11 125 3.8 697 11 231 1155 cubewano 697
(90568) 2004 GV9 4.2 703 8 4 680 10 211 1053 accepted 3:5 resonant 680
(145452) 2005 RN43 3.9 697 11 3.9 679 11 221 1103 possible cubewano 679
Ixion 3.8 674 12 3.6 650 15 253 1266 accepted 2:3 resonant 650
Varda 3.8 670 12 265 3.4 705 16 278 1388 possible cubewano 705
(202421) 2005 UQ513 3.8 670 12 3.4 498 31 278 1388 cubewano 498
(55565) 2002 AW197 3.9 659 12 3.5 768 12 265 1326 accepted cubewano 768
Chaos 5 612 5 4.8 600 6 146 729 cubewano 600
(229762) 2007 UK126 3.7 612 17 3.4 599 21 278 1388 SDO 599
(278361) 2007 JJ43 4.3 598 10 3.9 221 1103 cubewano 598
(84522) 2002 TC302 4.2 591 12 3.8 584 16 231 1155 2:5 resonant 584
(78799) 2002 XW93 5.4 584 4 5.5 106 528 SDO 584
(230965) 2004 XA192 4.4 584 10 4 339 39 211 1053 1:2 resonant 339
2010 KZ39 4.4 584 10 4 211 1053 cubewano 584
2013 FZ27 4.4 584 10 4 211 1053 cubewano 584
2012 VP113 4.4 584 10 4 211 1053 detached 584
2010 RF43 4.5 571 9 4.1 201 1006 SDO 571
2002 XV93 5.4 564 4 5 549 6 133 665 2:3 resonant 549
2003 UZ413 4.6 558 9 4.2 192 960 2:3 resonant 558
(42301) 2001 UR163 4.6 558 9 4.2 192 960 possible SDO 558
2008 ST291 4.6 558 9 4.2 192 960 detached 558
2010 FX86 4.7 545 9 4.3 183 917 cubewano 545
2006 QH181 4.7 545 9 4.3 183 917 SDO 545
2010 RE64 4.7 545 9 4.3 183 917 SDO 545
2014 UM33 4.7 541 8 4.3 183 917 cubewano 541
(84922) 2003 VS2 4.1 537 15 4.2 523 13 192 960 2:3 resonant 523
2004 NT33 4.8 533 8 4.4 423 17 175 876 cubewano 423
2004 XR190 4.8 533 8 4.4 175 876 detached 533
(145451) 2005 RM43 4.8 533 8 4.4 175 876 possible SDO 533
(120348) 2004 TY364 4.9 521 8 4.5 167 837 2:3 resonant 521
2008 OG19 5 509 8 4.6 160 799 SDO 509
2010 VK201 5 509 8 4.6 160 799 cubewano 509
2007 JH43 5 497 7 4.7 153 763 2:3 resonant 497
2003 QX113 5 497 7 4.7 153 763 SDO 497
(308379) 2005 RS43 5.6 495 4 5.3 116 579 1:2 resonant 495
(82075) 2000 YW134 5.1 486 7 4.8 146 729 detached 486
(175113) 2004 PF115 4.5 482 12 4.4 406 19 175 876 2:3 resonant 406
(307982) 2004 PG115 5.2 475 7 4.9 139 696 SDO 475
(119979) 2002 WC19 5.2 475 7 4.9 139 696 1:2 resonant 475
2007 XV50 5.2 475 7 4.9 139 696 cubewano 475
(315530) 2008 AP129 5.2 475 7 4.9 139 696 3:5 resonant 475
2010 EK139 3.8 475 25 3.8 470 24 231 1155 SDO 470
(307616) 2003 QW90 5.7 474 4 5.4 111 553 cubewano 474
(26375) 1999 DE9 5.2 474 7 5.1 461 8 127 635 possible SDO 461
(35671) 1998 SN165 5.7 473 4 5.6 393 7 101 504 cubewano 393
(145480) 2005 TB190 4.4 469 15 4.6 464 12 160 799 detached 464
(119951) 2002 KX14 4.9 468 10 4.4 175 876 2:3 resonant 468
(120132) 2003 FY128 5.1 467 8 4.9 460 9 139 696 SDO 460
Huya 5 466 8 4.9 458 9 139 696 accepted 2:3 resonant 458
2010 RF64 5.3 464 6 5 133 665 cubewano 464
2010 TJ 5.3 464 6 5 133 665 SDO 464
2010 VZ98 5.3 464 6 5 133 665 SDO 464
2011 FW62 5.3 464 6 5 133 665 2:3 resonant 464
(84719) 2002 VR128 5.6 459 5 5.7 449 5 96 481 2:3 resonant 449
1999 CD158 5.4 454 6 5.1 127 635 4:7 resonant 454
2013 FC28 5.4 454 6 5.1 127 635 cubewano 454
2010 EL139 5.4 454 6 5.1 127 635 2:3 resonant 454
2003 QX111 6.8 453 2 6.8 58 290 2:3 resonant 453
2006 HH123 5.4 452 6 5.2 121 606 2:5 resonant 452
2001 QF298 5.4 421 7 5.1 408 10 127 635 2:3 resonant 408
2002 GD32 6 417 4 5.7 96 481 cubewano 417
(303775) 2005 QU182 3.8 415 33 3.5 416 41 265 1326 SDO 416
(144897) 2004 UX10 4.8 409 14 4.5 361 21 167 837 possible 2:3 resonant 361
(26181) 1996 GQ21 5.5 383 8 5.2 121 606 SDO 383
2008 UA332 5.5 383 8 5.2 121 606 cubewano 383
2008 NW4 5.5 383 8 5.2 121 606 cubewano 383
(305543) 2008 QY40 5.5 383 8 5.2 121 606 SDO 383
2010 HE79 5.5 383 8 5.2 121 606 2:3 resonant 383
2010 ET65 5.5 383 8 5.2 121 606 SDO 383
2013 JW63 5.5 383 8 5.2 121 606 1:2 resonant 383
2011 GM27 5.5 383 8 5.2 121 606 cubewano 383
2011 JF31 5.6 367 8 5.3 116 579 cubewano 367
2010 RO64 5.6 367 8 5.3 116 579 cubewano 367
2010 JK124 5.6 367 8 5.3 116 579 2:3 resonant 367
1999 CL119 6.2 367 4 6 84 419 cubewano 367
2000 CQ105 6.2 367 4 6 84 419 SDO 367
2002 CY248 5.6 367 8 5.3 116 579 cubewano 367
2002 PJ149 5.6 367 8 5.3 116 579 cubewano 367
2001 QX322 6.2 367 4 6 84 419 SDO 367
2003 UA414 5.6 367 8 5.3 116 579 cubewano 367
(126154) 2001 YH140 5.7 352 8 5.4 111 553 cubewano 352
2001 QS297 5.7 352 8 5.4 111 553 cubewano 352
2000 KK4 6.3 352 4 6.1 80 400 cubewano 352
2000 PE30 6.3 352 4 6.1 80 400 SDO 352
(82155) 2001 FZ173 6.3 352 4 6.1 80 400 SDO 352
(48639) 1995 TL8 5.7 352 8 5.4 111 553 detached 352
2010 ER65 5.7 352 8 5.4 111 553 detached 352
2008 CT190 5.7 352 8 5.4 111 553 SDO 352
2010 TR19 5.7 352 8 5.4 111 553 SDO 352
2010 TY53 5.7 352 8 5.4 111 553 2:3 resonant 352
2010 VW11 5.7 352 8 5.4 111 553 SDO 352
(15874) 1996 TL66 5.4 344 11 5.4 339 11 111 553 accepted SDO 339
(135182) 2001 QT322 6.4 342 4 6.2 76 382 cubewano 342
2001 XD255 5.8 337 8 5.5 106 528 2:3 resonant 337
2002 GH32 5.8 337 8 5.5 106 528 3:5 resonant 337
2002 XH91 5.8 337 8 5.5 106 528 cubewano 337
2010 VR11 5.8 337 8 5.5 106 528 cubewano 337
2013 FB28 5.8 337 8 5.5 106 528 cubewano 337
2007 PS45 5.8 337 8 5.5 106 528 cubewano 337
2007 TG422 6.4 337 4 6.2 76 382 SDO 337
(312645) 2010 EP65 5.8 337 8 5.5 106 528 1:2 resonant 337
(82158) 2001 FP185 6.4 336 5 6 84 419 SDO 336
2001 KA77 5.6 324 10 5 133 665 cubewano 324
(148209) 2000 CR105 6.5 323 4 6.3 73 365 detached 323
2001 QC298 6.5 323 4 6.3 73 365 cubewano 323
2010 AH2 5.9 323 8 5.6 101 504 1:2 resonant 323
2010 RN64 5.9 323 8 5.6 101 504 cubewano 323
2010 PK66 5.9 323 8 5.6 101 504 cubewano 323
2010 PU75 5.9 323 8 5.6 101 504 SDO 323
2007 JF43 5.9 323 8 5.6 101 504 2:3 resonant 323
2012 XR157 5.9 323 8 5.6 101 504 1:2 resonant 323
2011 HP83 5.9 323 8 5.6 101 504 SDO 323
(307251) 2002 KW14 5.9 322 8 5 133 665 cubewano 322
2007 OC10 5.4 315 13 5.7 96 481 SDO 315
2004 VN112 6.6 310 4 6.4 70 349 detached 310
2004 OJ14 6.6 310 4 6.4 70 349 2:5 resonant 310
2003 UB292 6 309 8 5.7 96 481 cubewano 309
2002 GF32 6 309 8 5.7 96 481 2:3 resonant 309
2010 VQ11 6 309 8 5.7 96 481 cubewano 309
2014 WT69 6 309 8 5.7 96 481 detached 309
  1. ^ The measured diameter, else Brown's estimated diameter, else the diameter calculated from H using an assumed albedo of 8%.
  2. ^ Diameters with the text in red indicate that Brown's bot derived them from heuristically expected albedo.
  3. ^ The geometric albedo A is calculated from the measured absolute magnitude H and measured diameter D via the formula: A =\left ( \frac{1329\times10^{-H/5}}{D} \right ) ^2

See also[edit]

References[edit]

  1. ^ a b c Mike Brown. "The Dwarf Planets". Retrieved 2008-01-20. 
  2. ^ "Today we know of more than a dozen dwarf planets in the solar system [and] it is estimated that the ultimate number of dwarf planets we will discover in the Kuiper Belt and beyond may well exceed 10,000".The PI's Perspective
  3. ^ Dan Bruton. "Conversion of Absolute Magnitude to Diameter for Minor Planets". Department of Physics & Astronomy (Stephen F. Austin State University). Retrieved 2008-06-13. 
  4. ^ "IAU 2006 General Assembly: Result of the IAU Resolution votes". International Astronomical Union. 2006. Retrieved 2008-01-26. 
  5. ^ "Dwarf Planets". NASA. Retrieved 2008-01-22. 
  6. ^ "Plutoid chosen as name for Solar System objects like Pluto" (Press release). 
  7. ^ "AstDys (47171) 1999TC36 Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 2009-12-07. 
  8. ^ Savage, Don; Jones, Tammy; Villard, Ray (1995-04-19). "Asteroid or Mini-Planet? Hubble Maps the Ancient Surface of Vesta". Hubble Site News Release STScI-1995-20. Retrieved 2006-10-17. 
  9. ^ a b c d Mike Brown, How many dwarf planets are there in the outer solar system?
  10. ^ a b Tancredi, G. (2010). "Physical and dynamical characteristics of icy "dwarf planets" (plutoids)". Icy Bodies of the Solar System: Proceedings IAU Symposium No. 263, 2009. 
  11. ^ "List Of Trans-Neptunian Objects". Minor Planet Center. 
  12. ^ "List Of Centaurs and Scattered-Disk Objects". Minor Planet Center. 

External links[edit]