Extreme trans-Neptunian object explained

An extreme trans-Neptunian object (ETNO) is a trans-Neptunian object orbiting the Sun well beyond Neptune (30 AU) in the outermost region of the Solar System. An ETNO has a large semi-major axis of at least 150–250 AU. The orbits of ETNOs are much less affected by the known giant planets than all other known trans-Neptunian objects. They may, however, be influenced by gravitational interactions with a hypothetical Planet Nine, shepherding these objects into similar types of orbits. The known ETNOs exhibit a highly statistically significant asymmetry between the distributions of object pairs with small ascending and descending nodal distances that might be indicative of a response to external perturbations.

ETNOs can be divided into three different subgroups. The scattered ETNOs (or extreme scattered disc objects, ESDOs) have perihelia around 38–45 AU and an exceptionally high eccentricity of more than 0.85. As with the regular scattered disc objects, they were likely formed as result of gravitational scattering by Neptune and still interact with the giant planets. The detached ETNOs (or extreme detached disc objects, EDDOs), with perihelia approximately between 40–45 and 50–60 AU, are less affected by Neptune than the scattered ETNOs, but are still relatively close to Neptune. The sednoid or inner Oort cloud objects, with perihelia beyond 50–60 AU, are too far from Neptune to be strongly influenced by it.

Sednoids

See also: Sednoids.

Among the extreme trans-Neptunian objects are the sednoids, four objects with an outstandingly high perihelion: Sedna,, Leleākūhonua and . Sedna and are distant detached objects with perihelia greater than 70 AU. Their high perihelia keep them at a sufficient distance to avoid significant gravitational perturbations from Neptune. Previous explanations for the high perihelion of Sedna include a close encounter with an unknown planet on a distant orbit and a distant encounter with a random star or a member of the Sun's birth cluster that passed near the Solar System.[1] [2] [3]

Most distant objects from the Sun

See main article: List of Solar System objects most distant from the Sun.

Notable discoveries

Trujillo and Sheppard discoveries

Extreme trans-Neptunian objects discovered by astronomers Chad Trujillo and Scott S. Sheppard include:

Outer Solar System Origins Survey

The Outer Solar System Origins Survey has discovered more extreme trans-Neptunian objects, including:[9]

Since early 2016, ten more extreme trans-Neptunian objects have been discovered with orbits that have a perihelion greater than 30 AU and a semi-major axis greater than 250 AU bringing the total to sixteen (see table below for a complete list). Most TNOs have perihelia significantly beyond Neptune, which orbits from the Sun.[12] [13] Generally, TNOs with perihelia smaller than experience strong encounters with Neptune.[14] [15] Most of the ETNOs are relatively small, but currently relatively bright because they are near their closest distance to the Sun in their elliptical orbits. These are also included in the orbital diagrams and tables below.

TESS data search

Malena Rice and Gregory Laughlin applied a targeted shift-stacking search algorithm to analyze data from TESS sectors 18 and 19 looking for candidate outer Solar System objects.[16] Their search recovered known ETNOs like Sedna and produced 17 new outer Solar System body candidates located at geocentric distances in the range 80–200 AU, that need follow-up observations with ground-based telescope resources for confirmation. Early results from a survey with WHT aimed at recovering these distant TNO candidates have failed to confirm two of them.[17] [18]

List

Object! colspan=8
Barycentric Orbit (JD 2459600.5)Orbital planeBody
Stability
[19]

ω (°)
i (°)		HvCurrent
mag.
(km)

☊ or Ω (°)
ϖ=ω+Ω (°)
Stable 11,400 485 76.3 893 84.5 0.84 311.3 11.9 144.2 95.6 1.3 20.7 1,000
Stable 5,900 327 47.3 608 48.1 0.86 326.7 25.6 66.0 32.7 6.5 23.5 200
Unstable 11,260 502 35.6 969 38.5 0.93 285.6 18.6 112.9 38.4 6.5 22.5 200
Stable 35,300 1,090 65.2 2,110 78.0 0.94 117.8 11.7 300.8 58.5 5.5 24.6 220
Stable 6,600 342 48.6 636 73.1 0.86 347.1 21.6 130.9 118.0 6.5 25.2 200
Stable 4,300 261 80.4 443 84.0 0.69 293.6 24.1 90.7 24.3 4.0 23.3 600
? 6,780 358 32.2 684 33.4 0.91 225.1 15.8 294.4 8.0 23.4 100
Metastable 5,050 305 43.4 566 55.2 0.86 40.8 17.4 217.7 6.7 24.2 200
Unstable 6,900 370 36.1 705 37.6 0.90 311.6 29.6 67.6 19.2 8.7 24.6 70
? 9,950 463 46.0 880 47.4 0.90 262.9 12.4 104.8 7.6 6.1 23.1 200
Metastable 19,800 733 50.0 1,420 57.9 0.93 32.2 4.2 29.5 61.7 6.7 24.5 250
Unstable 5,590 326 38.1 614 39.3 0.88 265.4 6.5 94.6 7.0 23.2 140
Unstable 92,400 2,040 36.1 4,050 64.0 0.98 133.9 20.6 336.8 110.7 6.2 24.3 200
? 7,180 370 35.5 710 45.1 0.90 174.7 42.9 149.2 7.1 23.8 130
Stable 5,160 312 47.7 576 54.8 0.85 340.8 18.0 34.9 15.6 6.7 24.2 200
? 6,140 335 35.0 636 35.3 0.90 225.3 23.5 192.3 57.7 7.9 23.5 90
Metastable? 4,900 288 42.7 534 46.6 0.85 235.3 24.2 114.7 7.3 24.2 150
[20] ? 9,500 433 35.2 831 51.4 0.92 348.2 54.1 135.0 4.5 21.7 550[21]
? 5,400 309 34.0 585 34.4 0.89 244.6 12.9 273.1 8.3 23.9 100

(uo5m93)[22] 		Unstable? 4,620 278 39.5 516 41.7 0.86 43.4 6.8 166.0 8.7 25.0 80?
Unstable 5,510 314 38.5 589 42.9 0.88 129.3 8.8 46.1 8.5 24.9 80
Unstable 22,840 805 40.5 1,570 40.5 0.95 32.3 14.0 219.1 8.2 24.4 100
Metastable 8,920 421 45.7 796 59.9 0.89 64.8 12.1 8.6 73.4 6.2 24.1 250
? 3,830 250 39.1 451 42.3 0.84 200.3 21.5 174.7 15.0 7.8 24.2 90
? 6,550 350 42.7 658 44.5 0.88 162.9 4.8 219.4 22.3 6.7 23.4 160
Stable 4,500 252 45.0 459 54.8 0.82 302.9 8.5 192.4 7.7 25.2 140
? 42,600 1,220 46.8 2,400 81.1 0.96 109.2 18.2 109.2 6.4 25.6 180
?21,39577055.61,486—0.9318.673.4287.1305.7 (*)8.670
? 21,400 770 44.4 1,500 66.3 0.94 234.8 15.4 322.3 6.8 25.1 180
? 31,200 992 55.5 1,930 60.0 0.94 208.6 7.6 108.3 6.8 24.6 180
— >250 >30 — — >0.5 — 10~30 — 2~120 — — —
Hypothesized
Planet Nine

The most extreme case is that of, nicknamed Caju, which has both the highest inclination[26] and the farthest nodal distance; these properties make it a probable outlier within this population.[27]

External links

Notes and References

  1. Web site: Wall . Mike . 24 August 2011 . A Conversation With Pluto's Killer: Q & A With Astronomer Mike Brown . . 7 February 2016.
  2. Brown . Michael E. . Trujillo . Chadwick . Rabinowitz . David . 2004 . Discovery of a Candidate Inner Oort Cloud Planetoid . . 617 . 1 . 645–649 . astro-ph/0404456 . 2004ApJ...617..645B . 10.1086/422095. 7738201 .
  3. Web site: Brown . Michael E. . 28 October 2010 . There's something out there – part 2 . Mike Brown's Planets . 18 July 2016.
  4. Web site: Objects beyond Neptune provide fresh evidence for Planet Nine . The new evidence leaves astronomer Scott Sheppard of the Carnegie Institution for Science in Washington, D.C., "probably 90% sure there's a planet out there." But others say the clues are sparse and unconvincing. "I give it about a 1% chance of turning out to be real," says astronomer JJ Kavelaars, of the Dominion Astrophysical Observatory in Victoria, Canada.. 2016-10-25 .
  5. Web site: PLANET 9 SEARCH TURNING UP WEALTH OF NEW OBJECTS. 2016-08-30.
  6. Web site: Extreme New Objects Found At The Edge of The Solar System. 30 August 2016 .
  7. Web site: The Search for Planet Nine: New Finds Boost Case for Distant World. . 29 August 2016.
  8. Web site: HUNT FOR NINTH PLANET REVEALS NEW EXTREMELY DISTANT SOLAR SYSTEM OBJECTS. 2016-08-29.
  9. Shankman . Cory . etal . 2017 . OSSOS VI. Striking Biases in the detection of large semimajor axis Trans-Neptunian Objects . The Astronomical Journal . 154 . 4 . 50 . 1706.05348 . 10.3847/1538-3881/aa7aed . 2017AJ....154...50S. 10150/625487 . 3535702 . free .
  10. Web site: SETI Institute . 18 March 2016 . Exploring the outer Solar System: now in vivid colour - Michele Bannister (SETI Talks) . 28:17 . YouTube . 18 July 2016. SETI Institute .
  11. Bannister . Michele T. . etal . 2016 . A new high-perihelion a ~700 AU object in the distant Solar System . 48 . 113.08 . American Astronomical Society, DPS Meeting #48, Id. 113.08 . 2016DPS....4811308B.
  12. Eric . Hand . 20 January 2016 . Astronomers say a Neptune-sized planet lurks beyond Pluto . . 10.1126/science.aae0237 . 20 January 2016.
  13. News: Grush . Loren . 20 January 2016 . Our solar system may have a ninth planet after all — but not all evidence is in (We still haven't seen it yet) . . 18 July 2016 . The statistics do sound promising, at first. The researchers say there's a 1 in 15,000 chance that the movements of these objects are coincidental and don't indicate a planetary presence at all. ... 'When we usually consider something as clinched and air tight, it usually has odds with a much lower probability of failure than what they have,' says Sara Seager, a planetary scientist at MIT. For a study to be a slam dunk, the odds of failure are usually 1 in 1,744,278 . ... But researchers often publish before they get the slam-dunk odds, in order to avoid getting scooped by a competing team, Seager says. Most outside experts agree that the researchers' models are strong. And Neptune was originally detected in a similar fashion — by researching observed anomalies in the movement of Uranus. Additionally, the idea of a large planet at such a distance from the Sun isn't actually that unlikely, according to Bruce Macintosh, a planetary scientist at Stanford University..
  14. Batygin . Konstantin . Konstantin Batygin . Brown . Michael E. . Michael E. Brown . 2016 . Evidence for a distant giant planet in the Solar system . . 151 . 2 . 22 . 1601.05438 . 2016AJ....151...22B . 10.3847/0004-6256/151/2/22. 2701020 . free .
  15. Web site: Barbara . Koponyás . 10 April 2010 . Near-Earth asteroids and the Kozai mechanism . 5th Austrian-Hungarian Workshop in Vienna . 18 July 2016.
  16. Rice . Malena . Laughlin . Gregory . Exploring Trans-Neptunian Space with TESS: A Targeted Shift-stacking Search for Planet Nine and Distant TNOs in the Galactic Plane . . 1 . 3 . 81 (18 pp.) . December 2020 . 2010.13791. 10.3847/PSJ/abc42c . 2020PSJ.....1...81R . 225075671 . free .
  17. de la Fuente Marcos . Carlos . de la Fuente Marcos . Raúl . Vaduvescu . Ovidiu . Stanescu . Malin. 2022 . Distant trans-Neptunian object candidates from NASA's TESS mission scrutinized: fainter than predicted or false positives? . . 513 . 1 . L78–L82 . 2204.02230 . 2022MNRAS.513L..78D . 10.1093/mnrasl/slac036 . June 2022. free .
  18. Web site: Distant Trans-Neptunian Object Candidates: Fainter Than Predicted or False Positives? . 20 May 2022.
  19. Relative to hypothetical Planet Nine, The planet nine hypothesis . Konstantin . Batygin . Fred C. . Adams . Michael E. . Brown . Juliette C. . Becker. Physics Reports . 2019 . 805 . 1–53 . 10.1016/j.physrep.2019.01.009 . 1902.10103. 2019PhR...805....1B . 119248548 .
  20. Evaluating the Dynamical Stability of Outer Solar System Objects in the Presence of Planet Nine . DPS49 . American Astronomical Society . Juliette . Becker . 2017 . 14 March 2018.
  21. The hidden hand – Could a bizarre hidden planet be manipulating the solar system . Richard A. . Lovett . New Scientist International . 3156 . 41 . 16 December 2017 . 14 March 2018.
  22. Bannister . Michelle T. . etal . OSSOS. VII. 800+ Trans-Neptunian Objects — The complete data release . The Astrophysical Journal Supplement Series . 2018 . 236 . 1 . 18 . 10.3847/1538-4365/aab77a . 1805.11740. 2018ApJS..236...18B . 10150/628551 . 119078596 . free .
  23. Trujillo . Chadwick A. . Chad Trujillo . Sheppard . Scott S. . Scott S. Sheppard . 2014 . A Sedna-like body with a perihelion of 80 astronomical units . . 507 . 7493 . 471–474 . 2014Natur.507..471T . 10.1038/nature13156 . 24670765 . 4393431 . subscription . 2018-12-12 . https://web.archive.org/web/20141216183818/http://home.dtm.ciw.edu/users/sheppard/pub/TrujilloSheppard2014.pdf . 2014-12-16 . dead .
  24. Web site: Where is Planet Nine?. 20 January 2016. The Search for Planet Nine. Blog. https://web.archive.org/web/20160130091255/http://www.findplanetnine.com/p/blog-page.html. 30 January 2016. live.
  25. Alexandra . Witze . 2016 . Evidence grows for giant planet on fringes of Solar System . . 529 . 7586 . 266–7 . 2016Natur.529..266W . 10.1038/529266a . 26791699. free .
  26. Discovery and Dynamical Analysis of an Extreme Trans-Neptunian Object with a High Orbital Inclination . Becker . J. C. . DES Collaboration . etal . 2018 . . 156 . 2 . 81 . 10.3847/1538-3881/aad042 . 2018AJ....156...81B . 1805.05355. 55163842 . free .
  27. de la Fuente Marcos . Carlos . de la Fuente Marcos . Raúl . 12 September 2018 . A Fruit of a Different Kind: 2015 BP519 as an Outlier among the Extreme Trans-Neptunian Objects . . 2 . 3 . 167 . 1809.02571 . 2018RNAAS...2..167D . 10.3847/2515-5172/aadfec. 119433944 . free .

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