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Haumea family

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For the film character Haumeid, see She (1965 film).
The collisional family of Haumea (in green), other classical KBO (blue), Plutinos and other resonant objects (red) and SDO (grey). Radius is semi-major axis, angle orbital inclination.

The Haumea or Haumean family is the only identified trans-Neptunian collisional family; that is, the only group of trans-Neptunian objects (TNOs) with similar orbital parameters and spectra (nearly pure water-ice) that suggest they originated in the disruptive impact of a progenitor body.[1] Calculations indicate that it is probably the only trans-Neptunian collisional family.[2] Members are known as Haumeids.

Members

Brightest Haumea-family members:
Object (H) Diameter
albedo=0.7		 V–R[3]
Haumea 0.2 1,460 km 0.33
2002 TX300 3.4 332 km 0.36
2003 OP32 3.9 276 km 0.39
2005 RR43 4.1 252 km 0.41
2009 YE7 4.5 200 km
1995 SM55 4.6 191 km 0.39
2005 CB79 4.7 182 km 0.37
1996 TO66 4.8 174 km 0.39

Characteristics

Orbits of Haumea family members, sharing semimajor axes around 43 AU, and inclinations around 27°.

The dwarf planet Haumea is the largest member of the family, and the core of the differentiated progenitor; other identified members are the moons of Haumea and the Kuiper belt objects (55636) 2002 TX300, (24835) 1995 SM55, (19308) 1996 TO66, (120178) 2003 OP32, (145453) 2005 RR43, (86047) 1999 OY3, (416400) 2003 UZ117, (308193) 2005 CB79, 2003 SQ317[3] and (386723) 2009 YE7,[4] all with an ejection velocity from Haumea of less than 150 m/s.[5] The brightest Haumeids have absolute magnitudes (H) bright enough to suggest a size between 400 and 700 km in diameter, and so possible dwarf planets, if they had the albedos of typical TNOs; however, they are likely to be much smaller as it is thought they are water-icy bodies with high albedos. The dispersion of the proper orbital elements of the members is a few percent or less (5% for semi-major axis, 1.4° for the inclination and 0.08 for the eccentricity).[6] The diagram illustrates the orbital elements of the members of the family in relation to other TNOs.[citation needed]

The objects' common physical characteristics include neutral colours and deep infrared absorption features (at 1.5 and 2.0 μm) typical of water ice.[7][8]

Member orbits

Haumea collisional family[9]
Name Mean anomaly
M°		 Epoch Arg.Per
ω		 Long
Ω°		 Incl
i°		 Ecc
e		 Semi-major axis
a (AU)		 H Albedo
136108 Haumea 214.063 2458000.5 238.870 121.970 28.204 0.189 43.355 0.2 0.66
(19308) 1996 TO66 138.320 2458000.5 239.739 355.269 27.476 0.123 43.146 4.8 0.70
(24835) 1995 SM55 329.450 2458000.5 72.600 21.109 27.096 0.102 41.628 4.6 >0.07
(55636) 2002 TX300 76.403 2458000.5 338.275 324.607 25.862 0.123 43.065 3.4 0.88
(86047) 1999 OY3 63.504 2458000.5 304.611 301.800 24.215 0.173 43.853 6.8 0.70
(120178) 2003 OP32 72.441 2458000.5 68.383 182.936 27.213 0.108 43.183 3.9 0.70
(145453) 2005 RR43 46.801 2458000.5 278.412 85.810 28.553 0.136 43.039 4.1 0.703
(202421) 2005 UQ513[note 1] 228.669 2459000.5 222.480 307.532 25.699 0.145 43.329 3.6 0.31
(308193) 2005 CB79 320.837 2458000.5 91.146 112.852 28.646 0.147 43.555 4.7 0.70
(315530) 2008 AP129 53.949 2459000.5 56.289 14.875 27.419 0.136 41.546 4.7
(386723) 2009 YE7 182.135 2458000.5 99.742 141.608 29.090 0.148 44.165 4.5 0.70
(416400) 2003 UZ117 344.334 2459000.5 246.134 204.629 27.429 0.129 44.031 5.1
(523645) 2010 VK201 171.302 2459000.5 89.649 156.308 28.839 0.116 43.091 5.0
(543454) 2014 HZ199 66.295 2459000.5 85.268 57.101 27.835 0.154 43.249 5.0
2003 SQ317 6.947 2458000.5 191.808 176.338 28.619 0.077 42.489 6.2 0.05–0.5
2011 FW62 (2015 AJ281) 284.578 2459000.5 8.239 256.130 26.805 0.130 284.579 5.0
2014 LO28 313.026 2459000.5 104.587 287.074 25.535 0.121 43.219 5.3
2014 QW441 1.117 2459000.5 202.336 162.681 28.761 0.106 44.449 5.2
  1. ^ 2005 UQ513 displays a red spectrum unlike the rest of the Haumea family, although it dynamically belongs in the group.

Resonances with Neptune

The current orbits of the members of the family cannot be accounted for by the formational collision alone. To explain the spread of the orbital elements, an initial velocity dispersion of ≈ 400 m/s is required, but such a velocity spread should have dispersed the fragments much further. This problem applies only to Haumea itself; the orbital elements of all the other objects in the family require an initial velocity dispersion of just ≈ 140 m/s. To explain this mismatch in the required velocity dispersion, Brown and colleagues suggest that Haumea initially had orbital elements closer to those of the other members of the family and its orbit (especially the orbital eccentricity) changed after the collision. Unlike the other members of the family, Haumea is in an intermittent 7:12 resonance with Neptune,[10] which could have increased Haumea's eccentricity to its current value.[1]

The Haumea family occupies a region of the Kuiper belt where multiple resonances (including the 3:5, 4:7, 7:12, 10:17 and 11:19 mean motion resonances) interact, leading to the orbital diffusion of that collision family.[11] Beside the intermittent 7:12 resonance currently occupied by Haumea itself, other members of the family occupy some of the other resonances, and resonance hopping (switching from one resonance to another) is possible on a time scale of hundreds of millions of years. (19308) 1996 TO66, the first member of the Haumea family to be discovered, is currently in an intermittent 11:19 resonance.[12]

Formation and evolution

Collisional formation of the family requires a progenitor some 1660 km in diameter, with a density of ~2.0 g/cm3, similar to Pluto and Eris. During the formational collision, Haumea lost roughly 20% of its mass, mostly ice, and became denser.[1]

In addition to the effects of resonances with Neptune, there may be other complications in the origin of the family. It has been suggested that the material ejected in the initial collision may have coalesced into a large moon of Haumea, which gradually increased its distance from Haumea through tidal evolution, and was then later shattered in a second collision, dispersing its shards outwards.[5] This second scenario produces a velocity dispersion of ~190 m/s, considerably closer to the measured ~140 m/s velocity dispersion of the family members; it also avoids the difficulty of the observed ~140 m/s dispersion being much less than the ~900 m/s escape velocity of Haumea.[5]

Haumea may not be the only elongated, rapidly rotating, large object in the Kuiper belt. In 2002, Jewitt and Sheppard suggested that Varuna should be elongated, based on its rapid rotation. In the early history of the Solar System, the trans-Neptunian region would have contained many more objects than it does at present, increasing the likelihood of collisions between objects. Gravitational interaction with Neptune has since scattered many objects out of the Kuiper belt to the scattered disc.[citation needed]

The presence of the collisional family hints that Haumea and its "offspring" might have originated in the scattered disc. In today's sparsely populated Kuiper belt, the chance of such a collision occurring over the age of the Solar System is less than 0.1 percent. The family could not have formed in the denser primordial Kuiper belt because such a close-knit group would have been disrupted by Neptune's subsequent migration into the belt, which is thought to have been the cause of its current low density. Therefore, it appears likely that the dynamic scattered disc region, in which the possibility of such a collision is far higher, is the place of origin for the object which would become Haumea and its kin. Simulations suggest the probability of one such family in the Solar System is approximately 50%, so it is possible that the Haumea family is unique.[2]

The + marks 2005 RR43 (B−V=0.77, V−R=0.41) on this color plot of TNOs. All the other Haumea-family members are located to the lower left of this point.

Because it would have taken at least a billion years for the group to have diffused as far as it has, the collision that created the Haumea family is thought to have occurred very early in the Solar System's history.[13] This conflicts with the findings of Rabinowitz and colleagues who found in their studies of the group that their surfaces were remarkably bright; their colour suggests that they have recently (i.e. within the last 100 million years) been resurfaced by fresh ice. Over a timescale as long as a billion years, energy from the Sun would have reddened and darkened their surfaces, and no plausible explanation has been found to account for their apparent youth.[14]

However, more detailed studies of the visible and near infrared spectrum of Haumea[15] show it is a homogeneous surface covered by an intimate 1:1 mixture of amorphous and crystalline ice, together with no more than 8% organics. This high amount of amorphous ice on the surface confirms that the collisional event must have happened more than 100 million years ago. This result agrees with the dynamical studies and discards the assumption that the surfaces of these objects are young.[citation needed]

See also

References

  1. ^ a b c Brown, Michael E.; Barkume, Kristina M.; Ragozzine, Darin; Schaller, Emily L. (2007). "A collisional family of icy objects in the Kuiper belt" (PDF). Nature. 446 (7133): 294–296. Bibcode:2007Natur.446..294B. doi:10.1038/nature05619. PMID 17361177.
  2. ^ a b Harold F. Levison; Alessandro Morbidelli; David Vokrouhlický; William F. Bottke (2008). "On a Scattered Disc Origin for the 2003 EL61 Collisional Family—an Example of the Importance of Collisions in the Dynamics of Small Bodies". The Astronomical Journal. 136 (3): 1079–1088. arXiv:0809.0553. Bibcode:2008AJ....136.1079L. doi:10.1088/0004-6256/136/3/1079.
  3. ^ a b Snodgrass, Carry, Dumas, Hainaut (16 December 2009). "Characterisation of candidate members of (136108) Haumea's family". Astronomy and Astrophysics. 511: A72. arXiv:0912.3171. Bibcode:2010A&A...511A..72S. doi:10.1051/0004-6361/200913031.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ^ Trujillo, Sheppard and Schaller (14 February 2011). "A Photometric System for Detection of Water and Methane Ices on Kuiper Belt Objects". The Astrophysical Journal. 730 (2): 105. arXiv:1102.1971. Bibcode:2011ApJ...730..105T. doi:10.1088/0004-637X/730/2/105.
  5. ^ a b c Schlichting, Hilke E.; Re'em Sari (2009). "The Creation of Haumea's Collisional Family". The Astrophysical Journal. 700 (2): 1242–1246. arXiv:0906.3893. Bibcode:2009ApJ...700.1242S. doi:10.1088/0004-637X/700/2/1242.
  6. ^ de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (1 February 2018). "Dynamically correlated minor bodies in the outer Solar system". Monthly Notices of the Royal Astronomical Society. 474 (1): 838–846. arXiv:1710.07610. Bibcode:2018MNRAS.474..838D. doi:10.1093/mnras/stx2765.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  7. ^ Pinilla-Alonso, N.; Licandro, J.; Gil-Hutton, R.; Brunetto, R. (2007). "The water ice rich surface of (145453) 2005 RR43: A case for a carbon-depleted population of TNOs?". Astronomy and Astrophysics. 468: L25. arXiv:astro-ph/0703098. Bibcode:2007A&A...468L..25P. doi:10.1051/0004-6361:20077294.
  8. ^ Pinilla-Alonso, N.; Licandro, J.; Lorenzi, V. (July 2008). "Visible spectroscopy in the neighborhood of 2003EL{61}". Astronomy and Astrophysics. 489 (1): 455–458. arXiv:0807.2670. Bibcode:2008A&A...489..455P. doi:10.1051/0004-6361:200810226.
  9. ^ Proudfoot, Benjamin; Ragozzine, Darin (May 2019). "Modeling the Formation of the Family of the Dwarf Planet Haumea". The Astronomical Journal. arXiv:1904.00038. doi:10.3847/1538-3881/ab19c4.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  10. ^ Mark Buie, Orbit Fit and Astrometric record for 136108, 11 November 2019
  11. ^ Ragozzine & Brown, Candidate Members and Age Estimate of the Family of Kuiper Belt Object 2003 EL61, submitted 4 Sep 2007
  12. ^ D. Ragozzine; M. E. Brown (2007-09-04). "Candidate Members and Age Estimate of the Family of Kuiper Belt Object 2003 EL61". The Astronomical Journal. 134 (6): 2160–2167. arXiv:0709.0328. Bibcode:2007AJ....134.2160R. doi:10.1086/522334.
  13. ^ D. Ragozzine; M. E. Brown (2007). "Candidate Members and Age Estimate of the Family of Kuiper Belt Object 2003 EL61". The Astronomical Journal. 134 (6): 2160–2167. arXiv:0709.0328. Bibcode:2007AJ....134.2160R. doi:10.1086/522334.
  14. ^ David L. Rabinowitz; Bradley E. Schaefer; Martha W. Schaefer; Suzanne W. Tourtellotte (2008). "The Youthful Appearance of the 2003 EL61 Collisional Family". The Astronomical Journal. 136 (4): 1502–1509. arXiv:0804.2864. Bibcode:2008AJ....136.1502R. doi:10.1088/0004-6256/136/4/1502.
  15. ^ N. Pinilla-Alonso; R. Brunetto; J. Licandro; R. Gil-Hutton; T. L. Roush; G. Strazzulla (March 2009). "Study of the Surface of 2003 EL61, the largest carbon-depleted object in the trans-neptunian belt". Astronomy and Astrophysics. 496 (2): 547. arXiv:0803.1080. Bibcode:2009A&A...496..547P. doi:10.1051/0004-6361/200809733.
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