Haumea

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Haumea
Artist's conception of Haumea,
with its moons, Hiʻiaka and Namaka
 
Discovery
Discovered byBrown et al.; Ortiz et al. (neither official)
Discovery date2004 December 28 (Brown et al.); 2005 July (Ortiz et al.)
Designations
Designation
(136108) Haumea
2003 EL61
dwarf planet, plutoid, TNO (cubewano?)[1]
Orbital characteristics[2]
Epoch 2005-08-18 (JD 2 453 600.5)
Aphelion7 708 Gm (51.526 AU)
Perihelion5 260 Gm (35.164 AU)
6 484 Gm (43.335 AU)
Eccentricity0.188 74
104 234 d (285.4 a)
4.484 km/s
198.07°
Inclination28.19°
121.90°
239.51°
Known satellites2
Physical characteristics
Dimensions~1960 × 1518 × 996 km[3]
(~1400 km)
1150 +250
−100 km[4]
Mass(4.2 ± 0.1)×1021 kg[5]
Mean density
2.6–3.3 g/cm³[3]
0.44 m/s²
0.84 km/s
0.163 14 ± 0.000 01 d
(3.915 4 ± 0.000 2 h)[6]
Albedo0.7 ± 0.1[3]
Temperature32 ± 3 K
Spectral type
?
17.3 (opposition)[7]
0.17[2]

Haumea (Template:Pron-en), formal designation (136108) Haumea, is a dwarf planet in the Kuiper belt, roughly one-third the mass of Pluto. It was discovered in 2004 by a team headed by Mike Brown at Caltech and the Mauna Kea Observatory in the United States, and in 2005 by a team headed by J. L. Ortiz at the Instituto de Astrofísica de Andalucía at the Sierra Nevada Observatory in Spain, though the latter claim has been contested. On September 17, 2008, it was classified as a dwarf planet by the International Astronomical Union and named after Haumea, the Hawaiian goddess of childbirth.

Haumea is exceptional among the known trans-Neptunian objects because of its extreme elongation. Although its shape has not been directly observed, calculations from its light curve suggest it is an ellipsoid twice as long along its greatest axis as its shortest. Nonetheless, its gravity is believed sufficient for it to have relaxed into hydrostatic equilibrium, so it meets the definition of a dwarf planet. This elongation, along with other characteristics such as its unusually rapid rotation, high density, and high albedo—thought to be due to a layer of crystalline water ice on the surface—are thought to be the results of a giant collision. This left Haumea the largest member of a collisional family which includes both of its two moons.

Classification and name

Haumea is officially classified as a dwarf planet, meaning that it is believed to be large enough to have reached a state of hydrostatic equilibrium, but has not cleared its neighborhood of similar objects. Its orbital location is beyond Neptune, but neither in resonance with the planet nor capable of being gravitationally influenced by it, a situation which puts it in the classical Kuiper belt, the most numerous population of small icy bodies observed to date in the Kuiper belt region.[1] This trans-Neptunian location means it is classified in the plutoid subgroup of dwarf planets.[8] Although it is believed to be far from spherical, this is not a problem for its dwarf-planet status: its suspected ellipsoidal shape is the equilibrium state resulting from its rapid rotation, in much the same way as a water balloon stretches out when tossed with a spin, and is not due to Haumea having insufficient gravity to overcome the tensile strength of its material.[9]

When the Spanish discovery team announced the discovery of Haumea to the International Astronomical Union (IAU), it was given the temporary designation (136108) 2003 EL61 based on the date of the discovery image. Prior to this, the Caltech discovery team had used the nickname "Santa" among themselves, as they had first observed Haumea on December 28, 2004, just after Christmas,[10] though the discovery images had been taken on May 6, 2004.[11]

Following guidelines established by the IAU that objects in stable non-resonant orbits outside that of Neptune be given names of mythological beings associated with creation,[12] in September 2006 the Caltech team submitted formal names from Hawaiian mythology for both (136108) 2003 EL61 and its two known satellites, in order "to pay homage to the place where the satellites were discovered".[13] The names were proposed by David Rabinowitz of the Caltech team.[9] Haumea is the patron goddess of the island of Hawaiʻi, where the Mauna Kea Observatory is located. In addition, as the goddess of the earth,[14] she represents stone; this is appropriate because (136108) 2003 EL61 is inferred to be almost entirely solid rock, without the thick ice mantle over a small rock core considered typical of other known Kuiper belt objects.[15] Lastly, Haumea is the goddess of fertility and childbirth,[14] with many children who sprang from different parts of her body; this corresponds to the swarm of icy bodies thought to have broken off (136108) 2003 EL61 during an ancient collision. The two known moons, also believed to have been born in this manner, are thus named after two of Haumea's daughters, Hiʻiaka and Namaka.[15]

The IAU gives the discoverer of an object priority in naming it, and nearly always accepts their proposal. Due to the dispute over whether the Spanish team's discovery was legitimate, the naming of Haumea was delayed by several years. However, on September 17, 2008, the IAU officially accepted the Caltech team's proposal of "Haumea", as well as the names of the two moons, and formally classified (136108) 2003 EL61 as a dwarf planet. The Spanish team had proposed the name "Ataecina", and have expressed disappointment that they were not officially acknowledged as the discoverers and given naming rights.[16] However, neither team was given official acknowledgment, though Spain is listed as the place of discovery, and Ataecina, as a chthonic deity, would only have been an appropriate name for an object in orbital resonance with Neptune.[17]

Discovery controversy

On December 28, 2004, Mike Brown discovered Haumea on images they had taken with the 1.3 m SMARTS Telescope on May 6, 2004, while looking for what he hoped would be the tenth planet. Haumea (or Santa, as they called it at the time) clearly did not fit the bill, and Brown did not announce it. Instead he kept it under wraps, along with several other large TNOs, until additional observations could better establish the nature of the object. When his team discovered Haumea's moons, they realized that Haumea was more rocky than other TNOs, and that its moons were mostly ice. They then discovered a small family of nearby icy TNOs, and concluded that these were remnants of Haumea's icy mantle, which had been blasted off in a collision. On July 7, 2005, while finishing the paper describing the discovery, his daughter Lilah was born, and he put off the announcement.[10] On July 20 the Caltech team published an online abstract of a report they intended to use to announce the discovery at a conference in September 2005 (DPS 2005). In this Haumea was given the code K40506A.[18]

At around that time Pablo Santos Sanz, a student of José Luis Ortiz Moreno at the Instituto de Astrofísica de Andalucía at the Sierra Nevada Observatory in southern Spain, started looking through the backlog of photos the Ortiz team had started taking in December 2002. He says that in late July[when?] found Haumea on images taken on March 7, 9, and 10, 2003. In checking whether this was a known object, the team came across Brown's internet summary, describing a bright TNO much like the one they had just found. Googling the reference number K40506A on the morning of July 26, they found the Caltech observation logs of Haumea, but Sanz says these were not enough for Ortiz to tell if they were the same object.[19] The Ortiz team also checked with the Minor Planet Center (MPC), which had no record of this object. Wanting to establish priority, they emailed the MPC with their discovery on the night of July 27, 2005, giving a discovery date of March 7, 2003, and making no mention of the Caltech logs. The next morning they again accessed the Caltech logs, including observations from several additional nights. They then asked Reiner Stoss at the amateur Astronomical Observatory of Mallorca for further observations. Stoss found precovery images of Haumea in digitized Mount Palomar slides from 1955, and located Haumea with his own telescope that night, July 28. Within an hour,[18] the Ortiz team submitted a second report to the MPC that included this new data. Again, no mention was made of having accessed the Caltech logs.[20] The data was published by the MPC on July 29.[20] In a press release, the Ortiz team called it the "tenth planet".[16]

The same day as the MPC publication, Brown's group announced the discovery of another Kuiper belt object, Eris, which they believed to be more distant and larger than Pluto, as the tenth planet. The announcement was made earlier than planned, at the MPC's urging,[citation needed] to forestall the possibility of a similar controversy with that discovery,[citation needed] as the Caltech observation logs of Eris had by then also been publicly accessed.[10]

Brown, though disappointed at being scooped, congratulated Ortiz on their discovery. However, upon learning from web server records that a computer at the IP address of the Sierra Nevada Observatory had accessed his observation logs the day before the discovery announcement—logs which included enough information to allow the Ortiz team to precover Haumea in their 2003 images,—he came to suspect fraud. He emailed Ortiz informing him of the web-server logs tracing his IP address, and asked him for an explanation. Ortiz did not respond, and on August 9 the Caltech team filed a formal complaint with the IAU, accusing the Ortiz team of a serious breach of scientific ethics in failing to acknowledge the use of the Caltech data, and asked the MPC to strip them of discovery status.[21] Ortiz later admitted he had accessed the Caltech observation logs but denied any wrongdoing, stating this was merely part of verifying whether they had discovered a new object.[22]

IAU protocol is that discovery credit for a minor planet goes to whoever first submits a report to the MPC with enough positional data for a decent orbit determination. This was Ortiz et al., and they proposed the name Ataecina.[19] However, the dispute over who had actually discovered the object delayed the acceptance of a name and formal classification as a dwarf planet by the IAU. On 17 September 2008, the IAU announced that the two bodies in charge of naming dwarf planets, the Committee on Small Body Nomenclature (CSBN) and the Working Group for Planetary System Nomenclature ( WGPSN), had decided on the Caltech proposal of Haumea. At the CSBN, the name was decided by a single vote.[19] However, on the announcement the location of discovery was listed as the Sierra Nevada Observatory, and the name of the discoverer was left blank.[8][17] Brian Marsden, head of the IAU's MPC at Harvard, openly supported Brown's claim saying that "Sooner or later, posterity will realise what happened, and Mike Brown will get the full credit".[17] The Ortiz team have objected, suggesting that if Ataecina were not accepted the IAU could at least have chosen a third name favoring neither party, and accusing the IAU of political bias.[19]

Orbit and rotation

Orbits of Haumea (yellow) and Pluto (red), relative to that of Neptune (grey)

Haumea has a typical orbit for a classical trans-Neptunian object, with an orbital period of 285 Earth years, a perihelion of 35 AU, and high orbital inclination. The diagram at right shows the orbital position of Haumea in yellow, compared to Pluto in red and Neptune in grey, as of April 2006. Haumea passed aphelion in early 1992,[7] and is currently more than 50 AU from the Sun.

Haumea's orbit lies at a slightly higher inclination than the other members of its collisional family. This may be due to a possible 12:7 orbital resonance with Neptune. Such a resonance would have shifted its orbit over the course of the last billion years,[23] through the Kozai effect, which allows the exchange of an orbit's eccentricity for increased inclination.

Despite being the third brightest object in the Kuiper belt, Haumea's high orbital inclination of 28° (65% greater than Pluto's 17°) and its current position far from the ecliptic (where most earlier surveys took place), combined with its slow mean motion across the sky, made discovery of Haumea unlikely until recently.

Haumea rotates roughly once every four hours, faster than any other known equilibrium body in the solar system and indeed faster than any known body larger than 100 km in diameter.[3] Its short rotation period is likely to have been caused by the same giant impact which created its satellites and its collisional family.[24]

Physical characteristics

Size and composition

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The only way to estimate the size of a small, isolated trans-Neptunian object is to use the body's optical magnitude and location, and assuming a value for its albedo. For larger, brighter objects, their thermal emission can also be measured, which gives direct evidence for the albedo.[4] The mass can only be crudely estimated by assuming a value for its density. However, the addition of a satellite allows the mass of the system to be calculated directly from the satellite's orbit using Kepler's third law. It the case of Haumea, the result is 4.2 × 1021 kg, or 28% the mass of the Plutonian system. Since the Haumean moons are so small, nearly all of this mass is in Haumea.[5]

The calculated ellipsoid shape of Haumea, 1960×1518×996 km. At left are the minimum and maximum shapes seen at the equator (1960×996 and 1518×996 km); at right is the view from the pole (1960×1518 km).

Haumea displays large fluctuations in brightness over a period of 4 hours, indicating that it rotates faster than any other large object known in the Solar system. Although these fluctuations could be at least partially due to a mottled surface,[6] it is thought that Haumea has been distorted into a scalene ellipsoid by its four-hour rotational period, and that the alternating side view–end view–side view causes most of the fluctuation.[3] The rapid rotation and elongated shape are only possible with certain mass distributions, and the denser the object, the less elongated it would be for a given rotation. This constrains Haumea's density to around 2.6–3.3 g/cm³, suggesting a substantially rocky content.[note 1] The limits on mass and density place constrains on Haumea's possible dimensions.[3] The best fit to the data as of 2008 is that Haumea is approximately the diameter of Pluto along its longest axis and about half the diameter of Pluto at its poles. This would make it one of the largest trans-Neptunian objects discovered, and possibly fourth after Eris, Pluto, and Makemake. It would be larger than Sedna, Orcus, and Quaoar.[25]

Surface

The Gemini telescope obtained spectra of Haumea which show strong water ice features similar to the surface of Pluto's moon Charon. Trujillo, Brown, et al. report the presence of crystalline water ice.[26] Under conditions in the Kuiper belt, crystalline ice is unstable on timescales of 10 million years.[27] Therefore, the discovery of crystalline ice on the surface of any Kuiper belt object suggests a resurfacing processes that produces fresh ice. Similarly surprising is the inferred amount of ice, as Haumea's surface appears to be covered in pure ice in a proportion of 66% to 80%—the remainder being material of unknown composition.[26] The purity of the ice on Haumea's surface suggests that the object consists essentially of a thin layer of ice surrounding a core of rock.[26]

Haumea has an albedo greater than 0.6 (about as bright as snow)[3] which is consistent with the report of crystalline ice on the surface. This very high albedo though, does not appear to be unique among large TNOs. Recent measurements of Eris imply an even higher (inferred) albedo (0.86) for that object.[28]

Analysis of color variations in Haumea's light curve reveal shifts in color that cannot be accounted for by its rotational deformation, and suggest that there exists a region on Haumea's surface that is different both in color and in albedo from the object's average.[6]

Moons

Main articles: Moons of Haumea, Hi'iaka (moon), and Namaka (moon)

Two small satellites have been discovered orbiting Haumea, (136108) Haumea I Hiʻiaka and (136108) Haumea II Namaka.[8] They were both discovered in 2005, only a few years after occultations of Hiʻiaka with Haumea in 1999. Hiʻiakan occultations will not happen again until 2138.[29] Namaka went through five occultations between May and June 2008.[29] Mike Brown's team has calculated a better orbital solution for Namaka and think that the occultations might occur for a few more years.[10]

Hiʻiaka, nicknamed "Rudolph" by the Caltech team, was the first to be discovered, on January 26, 2005.[30] It is the outer and larger of the two, and orbits Haumea every 49 days. Strong absorption features at 1.5 and 2 micrometres in the infrared spectrum are consistent with water ice; their strength, greater than that of any other body in the Solar System,[31] suggests that water ice covers much of the surface.[31] The unusual spectrum, along with similar absorption lines on Haumea, led Brown et. al. to conclude that capture was an unlikely model for the system's formation, and that the Haumean moons must be fragments of Haumea itself.[23]

Namaka, nicknamed "Blitzen" by the Caltech team,[32] is the smaller, inner satellite of Haumea. Its discovery was announced on November 7, 2005. It is inclined approximately 40° from the larger moon, but as of 2008 its orbit is not yet known. Assuming a similar surface composition to the larger moon, its brightness implies a diameter 12% that of Haumea, or some 170 km.[citation needed]

Collisional family

Main article: Haumea family

Haumea is the largest member of a TNO collisional family, similar to asteroid families: a group of objects with similar orbital parameters and common physical characteristics, presumably with a common origin in a disruptive impact of the progenitor object of Haumea.[24] This family is the first to be identified among TNOs and includes Haumea and its moons, 2002 TX300, (24835) 1995 SM55, (19308) 1996 TO66, (120178) 2003 OP32 and (145453) 2005 RR43.[33]

The presence of the collisional family could imply 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 is less than 0.1 percent.[34] 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 migration into the belt—the believed cause of the belt's current low density.[34] 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 that generated Haumea and its kin.[34]

Because it would have taken at least a billion years for the group to have diffused as far as it has, the collision which created the Haumea family is believed to have occurred very early in the Solar System's history.[33] This conflicts with Rabinowitz et. al. findings that the surfaces of these objects are remarkably bright. Their color suggests that they have recently (i.e. within the last 100 million years) been resurfaced by fresh ice because over a timescale as long as a billion years, energy from the Sun would have reddened and darkened their surfaces. No plausible explanation has been found to account for their apparent youth.[35]

Notes

  1. ^ For comparison, Pluto, a typical icy object in Kuiper belt, has a density of 2.0 g/cm³, while the Earth's moon, which is mostly rock, has a density of 3.3 g/cm³.

References

  1. ^ a b "MPEC 2008-O05 : Distant Minor Planets (2008 AUG. 2.0 TT)". Minor Planet Center. 2008-07-17. Retrieved 2008-09-27.
  2. ^ a b "JPL Small-Body Database Browser: 136 108 (2003 EL61)". 2008-05-10 last obs. Retrieved 2008-06-11. {{cite web}}: Check date values in: |date= (help)
  3. ^ a b c d e f g D. L. Rabinowitz, K. M. Barkume, M. E. Brown, H. G. Roe, M. Schwartz, S. W. Tourtellotte, C. A. Trujillo (2006). "Photometric Observations Constraining the Size, Shape, and Albedo of 2003 EL61, a Rapidly Rotating, Pluto-Sized Object in the Kuiper Belt". The Astrophysical Journal. 639 (2): 1238–1251. doi:10.1086/499575. {{cite journal}}: |format= requires |url= (help); External link in |format= (help)CS1 maint: multiple names: authors list (link)
  4. ^ a b John Stansberry, Will Grundy, Mike Brown, Dale Cruikshank, John Spencer, David Trilling, Jean-Luc Margot (2007-02-20). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope". University of Arizona, Lowell Observatory, California Institute of Technology, NASA Ames Research Center, Southwest Research Institute, Cornell University. Retrieved 2008-07-27.{{cite web}}: CS1 maint: multiple names: authors list (link)
  5. ^ a b M. E. Brown, A. H. Bouchez, D. L. Rabinowitz, R. Sari, C. A. Trujillo, M. A. van Dam, R. Campbell, J. Chin, S. Hartman, E. Johansson, R. Lafon, D. LeMignant, P. Stomski, D. Summers, P. L. Wizinowich (October 2005). "Keck Observatory laser guide star adaptive optics discovery and characterization of a satellite to large Kuiper belt object 2003 EL61". The Astrophysical Journal Letters. 632: L45. doi:10.1086/497641. {{cite journal}}: |format= requires |url= (help); External link in |format= (help)CS1 maint: multiple names: authors list (link)
  6. ^ a b c Pedro Lacerda, David Jewitt and Nuno Peixinho (2008-04-02). "High-Precision Photometry of Extreme KBO 2003 EL61". The Astronomical Journal. 135: 1749–1756. Retrieved 2008-09-22.
  7. ^ a b "HORIZONS Web-Interface". JPL Solar System Dynamics. Retrieved 2008-07-02. {{cite web}}: External link in |publisher= (help)
  8. ^ a b c "USGS Gazetteer of Planetary Nomenclature". Retrieved 2008-09-17.
  9. ^ a b "IAU names fifth dwarf planet Haumea". IAU Press Release. 2008-09-17. Retrieved 2008-09-17.
  10. ^ a b c d Mike Brown (2008-09-17). "Mike Brown's Planets: Haumea". Retrieved 2008-09-22.
  11. ^ Mike Brown. "The discovery of 2003 UB313 Eris, largest known dwarf planet". CalTech. Retrieved 2008-09-23.
  12. ^ "Naming of astronomical objects: Minor planets". International Astronomical Union. Retrieved 2008-11-17.
  13. ^ Mike Brown (2008-09-17). "Dwarf planets: Haumea". CalTech. Retrieved 2008-09-18.
  14. ^ a b Robert D. Craig (2004). Handbook of Polynesian Mythology. ABC-CLIO. p. 128.
  15. ^ a b "News Release - IAU0807: IAU names fifth dwarf planet Haumea". International Astronomical Union. 2008-09-17. Retrieved 2008-09-18.
  16. ^ a b "Estados Unidos «conquista» Haumea". ABC.es news. 2008-09-20. Retrieved 2008-09-18. Template:Es icon
  17. ^ a b c Rachel Courtland (2008-09-19). "Controversial dwarf planet finally named 'Haumea'". NewScientistSpace. Retrieved 2008-09-19.
  18. ^ a b Michael E Brown. "The electronic trail of the discovery of 2003 EL61". CalTech. Retrieved 2006-08-16.
  19. ^ a b c d Pablo Santos Sanz (2008-26-09). "La historia de Ataecina vs Haumea". infoastro.com. Retrieved 2008-09-29. {{cite web}}: Check date values in: |date= (help) Template:Es icon
  20. ^ a b "Minor Planet Electronic Circular 2005-O36 : 2003 EL61". 2005-07-29. Retrieved 2008-09-23.
  21. ^ "One Find, Two Astronomers:An Ethical Brawl". New York Times. 2005-09-13. Retrieved 2006-08-16. {{cite news}}: Unknown parameter |name= ignored (help)
  22. ^ "Astronomer denies improper use of web data". NewScientist.com. 2005-09-21. Retrieved 2006-08-16. {{cite news}}: Unknown parameter |name= ignored (help)
  23. ^ a b Michael E. Brown. "The largest Kuiper belt objects" (PDF). CalTech. Retrieved 2008-09-19.
  24. ^ a b Michael E. Brown, Kristina M. Barkume; Darin Ragozzine; Emily L. Schaller (2007-01-19). "A collisional family of icy objects in the Kuiper belt". Nature. 446 (7133): 294–296. doi:10.1038/nature05619. {{cite journal}}: |access-date= requires |url= (help)CS1 maint: multiple names: authors list (link)
  25. ^ J. Stansberry, W. Grundy, M. Brown; et al. (2008-04-17). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope" (abstract). The Solar System beyond Neptune. University of Arizona Press. Retrieved 2008-08-04. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  26. ^ a b c Chadwick A. Trujillo, Michael E. Brown, Kristina Barkume, Emily Shaller, David Rabinowitz (February 2007). "The Surface of 2003 EL61 in the Near Infrared". The Astrophysical Journal. 655: 1172–1178. doi:10.1086/509861. {{cite journal}}: |format= requires |url= (help); External link in |format= (help)CS1 maint: multiple names: authors list (link)
  27. ^ "Charon: An ice machine in the ultimate deep freeze". Gemini Observatory. 2007-07-17. Retrieved 2007-07-18.
  28. ^ M. E. Brown, E.L. Schaller, H.G. Roe, D. L. Rabinowitz, C. A. Trujillo (2006). "Direct measurement of the size of 2003 UB313 from the [[Hubble Space Telescope]]" (PDF). The Astronomical Journal. 643 (2): L61–L63. doi:10.1086/504843. {{cite journal}}: URL–wikilink conflict (help)CS1 maint: multiple names: authors list (link)
  29. ^ a b Mike Brown (2008-05-18). "Moon shadow Monday (fixed)". Retrieved 2008-09-27.
  30. ^ M. E. Brown, A. H. Bouchez, D. Rabinowitz. R. Sari, C. A. Trujillo, M. van Dam, R. Campbell, J. Chin, S. Hardman, E. Johansson, R. Lafon, D. Le Mignant, P. Stomski, D. Summers, and P. Wizinowich (2005-09-02). "Keck Observatory Laser Guide Star Adaptive Optics Discovery and Characterization of a Satellite to the Large Kuiper Belt Object 2003 EL61". The Astrophysical Journal Letters. 632: L45–L48. doi:10.1086/497641.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  31. ^ a b K. M Barkume, M. E. Brown, and E. L. Schaller (March 2006). preprint "Water Ice on the Satellite of Kuiper Belt Object 2003 EL61". The Astrophysical Journal. 640: L87–L89. doi:10.1086/503159. {{cite journal}}: Check |url= value (help)CS1 maint: multiple names: authors list (link)
  32. ^ Kenneth Chang (2007-03-20). "Piecing Together the Clues of an Old Collision, Iceball by Iceball". New York Times.
  33. ^ a b 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. doi:10.1086/522334. Retrieved 2008-09-19.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  34. ^ a b c Harold F. Levison, Alessandro Morbidelli, David Vokrouhlický and William F. Bottke (2008-04-14). "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: 1079–1088. doi:10.1088/0004-6256/136/3/1079. Retrieved 2008-09-19.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  35. ^ David L. Rabinowitz, Bradley E. Schaefer, Martha W. Schaefer, Suzanne W. Tourtellotte (2008-04-17). "The Youthful Appearance of the 2003 EL61 Collisional Family". ArXiv.org. Retrieved 2008-09-20.{{cite journal}}: CS1 maint: multiple names: authors list (link)

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Haumea&oldid=241602777"