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.
| 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 |
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 , (612620) 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]
| Name | Mean anomaly M° | Epoch | Arg.Per ω | Long Ω° | Incl i° | Ecc e | Semi-major axis a (AU) | H | Albedo |
|---|---|---|---|---|---|---|---|---|---|
| 136108 Haumea | 217.772 | 2459000.5 | 238.779 | 122.163 | 28.214 | 0.195 | 43.182 | 0.2 | 0.66 |
| (19308) 1996 TO66 | 139.355 | 2459000.5 | 242.001 | 355.158 | 27.381 | 0.120 | 43.345 | 4.8 | 0.70 |
| (24835) 1995 SM55 | 334.598 | 2459000.5 | 70.848 | 21.016 | 27.042 | 0.101 | 41.658 | 4.6 | >0.07 |
| (55636) 2002 TX300 | 77.718 | 2459000.5 | 340.338 | 324.409 | 25.832 | 0.126 | 43.270 | 3.4 | 0.88 |
| (86047) 1999 OY3 | 64.735 | 2459000.5 | 306.961 | 301.717 | 24.154 | 0.173 | 44.158 | 6.8 | 0.70 |
| (120178) 2003 OP32 | 72.355 | 2459000.5 | 71.889 | 182.016 | 27.135 | 0.109 | 43.496 | 4.0 | 0.70 |
| (145453) 2005 RR43 | 50.329 | 2459000.5 | 278.004 | 85.792 | 28.574 | 0.139 | 43.112 | 4.0 | 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 | 322.348 | 2459000.5 | 92.975 | 112.936 | 28.692 | 0.142 | 43.212 | 4.6 | 0.70 |
| (315530) 2008 AP129 | 53.949 | 2459000.5 | 56.289 | 14.875 | 27.419 | 0.136 | 41.546 | 4.7 | |
| (386723) 2009 YE7 | 183.830 | 2459000.5 | 101.182 | 141.381 | 29.114 | 0.147 | 44.203 | 4.3 | 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 | |
| (612620) 2003 SQ317 | 11.059 | 2459000.5 | 191.080 | 176.268 | 28.537 | 0.082 | 42.736 | 6.6 | 0.05–0.5 |
| (673087) 2015 AJ281 | 284.578 | 2459000.5 | 8.239 | 256.130 | 26.805 | 0.130 | 43.199 | 5.0 | |
| (671467) 2014 LO28 | 313.026 | 2459000.5 | 104.587 | 287.074 | 25.535 | 0.121 | 43.219 | 5.3 | |
| (653589) 2014 QW441 | 1.117 | 2459000.5 | 202.336 | 162.681 | 28.761 | 0.106 | 44.449 | 5.2 |
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]
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]
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 ]
A classical Kuiper belt object, also called a cubewano ( "QB1-o"), is a low-eccentricity Kuiper belt object (KBO) that orbits beyond Neptune and is not controlled by an orbital resonance with Neptune. Cubewanos have orbits with semi-major axes in the 40–50 AU range and, unlike Pluto, do not cross Neptune's orbit. That is, they have low-eccentricity and sometimes low-inclination orbits like the classical planets.
The Kuiper belt is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times as wide and 20–200 times as massive. Like the asteroid belt, it consists mainly of small bodies or remnants from when the Solar System formed. While many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles, such as methane, ammonia, and water. The Kuiper belt is home to most of the objects that astronomers generally accept as dwarf planets: Orcus, Pluto, Haumea, Quaoar, and Makemake. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, may have originated in the region.
A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has an orbital semi-major axis of 30.1 astronomical units (AU).
Haumea is a dwarf planet located beyond Neptune's orbit. It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory, and formally announced in 2005 by a team headed by José Luis Ortiz Moreno at the Sierra Nevada Observatory in Spain, who had discovered it that year in precovery images taken by the team in 2003. From that announcement, it received the provisional designation 2003 EL61. On 17 September 2008, it was named after Haumea, the Hawaiian goddess of childbirth, under the expectation by the International Astronomical Union (IAU) that it would prove to be a dwarf planet. Nominal estimates make it the third-largest known trans-Neptunian object, after Eris and Pluto, and approximately the size of Uranus's moon Titania. Precovery images of Haumea have been identified back to 22 March 1955.
(19308) 1996 TO66 (provisional designation 1996 TO66) is a trans-Neptunian object that was discovered in 1996 by Chadwick Trujillo, David Jewitt and Jane Luu. Until 20000 Varuna was discovered, it was the second-largest known object in the Kuiper belt, after Pluto.
(55565) 2002 AW197 (provisional designation 2002 AW197) is a classical, non-resonant trans-Neptunian object from the Kuiper belt in the outermost region of the Solar System, also known as a cubewano. With a likely diameter of at least 600 kilometers (400 miles), it is approximately tied with 2002 MS4 and 2013 FY27 (to within measurement uncertainties) as the largest unnamed object in the Solar System. It was discovered at Palomar Observatory in 2002.
In astronomy, a resonant trans-Neptunian object is a trans-Neptunian object (TNO) in mean-motion orbital resonance with Neptune. The orbital periods of the resonant objects are in a simple integer relations with the period of Neptune, e.g. 1:2, 2:3, etc. Resonant TNOs can be either part of the main Kuiper belt population, or the more distant scattered disc population.
(55636) 2002 TX300 is a bright Kuiper belt object in the outer Solar System estimated to be about 286 kilometres (178 mi) in diameter. It is a large member of the Haumea family that was discovered on 15 October 2002 by the Near-Earth Asteroid Tracking (NEAT) program.
Hiʻiaka is the larger, outer moon of the trans-Neptunian dwarf planet Haumea. It is named after one of the daughters of Haumea, Hiʻiaka, the patron goddess of the Big Island of Hawaii. It orbits once every 49.12±0.03 d at a distance of 49880±198 km, with an eccentricity of 0.0513±0.0078 and an inclination of 126.356±0.064°. Assuming its estimated diameter of over 300 km is accurate, it may be the fourth- or fifth-largest known moon of a Trans-Neptunian object, after Pluto I Charon, Eris I Dysnomia, Orcus I Vanth, and possibly Varda I Ilmarë and Salacia I Actaea.
Namaka is the smaller, inner moon of the trans-Neptunian dwarf planet Haumea. Discovered in 2005, it is named after Nāmaka, the goddess of the sea in Hawaiian mythology and one of the daughters of Haumea. Namaka is notable for its unusual, highly-perturbed orbit that is heavily influenced by the larger, outer moon Hi'iaka.
(208996) 2003 AZ84 (provisional designation 2003 AZ84) is a trans-Neptunian object with a possible moon located in the outer regions of the Solar System. It is approximately 940 kilometers across its longest axis, as it has an elongated shape. It belongs to the plutinos – a group of minor planets named after its largest member Pluto – as it orbits in a 2:3 resonance with Neptune in the Kuiper belt. It is the third-largest known plutino, after Pluto and Orcus. It was discovered on 13 January 2003, by American astronomers Chad Trujillo and Michael Brown during the NEAT survey using the Samuel Oschin telescope at Palomar Observatory.
(84922) 2003 VS2 is a trans-Neptunian object discovered by the Near Earth Asteroid Tracking program on 14 November 2003. Like Pluto, it is in a 2:3 orbital resonance with Neptune and is thus a plutino. Analysis of light-curve suggests that it is not a dwarf planet.
(24835) 1995 SM55 (provisional designation 1995 SM55) is a trans-Neptunian object and member of the Haumea family that resides in the Kuiper belt, located in the outermost region of the Solar System. It was discovered on 19 September 1995, by American astronomer Nichole Danzl of the Spacewatch program at Kitt Peak National Observatory near Tucson, Arizona, in the United States. It measures approximately 200 kilometers in diameter and was the second-brightest known object in the Kuiper belt, after Pluto, until 1996 TO66 was discovered.
(120178) 2003 OP32, also written as (120178) 2003 OP32, is a trans-Neptunian object (TNO) that resides in the Kuiper belt. It was discovered on July 26, 2003 by Michael E. Brown, Chad Trujillo and David L. Rabinowitz at Palomar Mountain in California.
(145453) 2005 RR43 (provisional designation 2005 RR43) is a trans-Neptunian object (TNO) estimated to be about 250 km in diameter. It was discovered on 9 September 2005 by Andrew Becker, Andrew Puckett and Jeremy Kubica at Apache Point Observatory in Sunspot, New Mexico.
(86047) 1999 OY3 (provisional designation 1999 OY3) is a trans-Neptunian object that resides in the Kuiper belt beyond Pluto. It was discovered on July 18, 1999, at the Mauna Kea Observatory, Hawaii, USA.
(202421) 2005 UQ513 (provisional designation 2005 UQ513) is a cubewano with an absolute magnitude of 3.97. Its spectrum has a weak signature of absorption by water ice. Like Quaoar, it has a very red spectrum, which indicates that its surface probably contains many complex, processed organic molecules. Its light curve shows variations of Δm=0.3 mag, but no period has been determined.
The dwarf planet Haumea has two known moons, Hiʻiaka and Namaka, named after Hawaiian goddesses. These small moons were discovered in 2005, from observations of Haumea made at the large telescopes of the W. M. Keck Observatory in Hawaii.
(469306) 1999 CD158 (provisional designation 1999 CD158) is a trans-Neptunian object from the circumstellar disc of the Kuiper belt, located in the outermost region of the Solar System. The relatively bright hot classical Kuiper belt object measures approximately 310 kilometers (190 miles) in diameter. It was discovered on 10 February 1999, by American astronomers Jane Luu, David Jewitt, and Chad Trujillo at Mauna Kea Observatories on the Big Island of Hawaii, United States.
(416400) 2003 UZ117 (provisional designation 2003 UZ117) is a trans-Neptunian object and suspected member of the Haumea family, located in the Kuiper belt in the outermost region of the Solar System. It was discovered on 24 October 2003, by astronomers of the Spacewatch survey project at Kitt Peak Observatory, Arizona. The object may also be a non-resonant cubewano.
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