Английская Википедия:Hiʻiaka (moon)

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HiШаблон:Okinaiaka is the larger, outer moon of the trans-Neptunian dwarf planet Haumea. It is named after one of the daughters of Haumea, [[HiШаблон:Okinaiaka]], the patron goddess of the Big Island of Hawaii. It orbits once every Шаблон:Val at a distance of Шаблон:Val, with an eccentricity of Шаблон:Val and an inclination of Шаблон:Val. 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.

Discovery

HiШаблон:Okinaiaka was the first satellite discovered around Haumea. It was discovered on 26 January 2005 and nicknamed "Rudolph" by the discovery team before being assigned an official name.

Physical characteristics

Size and brightness

Its measured brightness is Шаблон:Val, translating into a diameter of about 22% of its primary, or in the range of Шаблон:Val, assuming similar infrared albedo. To put this in perspective, if Hiʻiaka were in the asteroid belt, it would be larger than all but the four largest asteroids, after 1 Ceres, 2 Pallas, 4 Vesta, and 10 Hygiea. In spite of its relatively large size, however, lightcurve studies suggest that Hiʻiaka is not a gravitationally collapsed spheroid; they further suggest that Hiʻiaka is not tidally locked and has a rotation period of about 9.8 hours.

Mass

The mass of HiШаблон:Okinaiaka is estimated to be Шаблон:Val using precise relative astrometry from the Hubble Space Telescope and Keck Telescope and applying 3-body, point-mass model to the Haumean system.

Spectrum and composition

The near infrared spectrum of HiШаблон:Okinaiaka is dominated by water-ice absorption bands, which means that its surface is made mainly of water ice. The presence of the band centered at Шаблон:Val indicates that the surface water ice is primarily in the crystalline form. Currently it is unclear why water ice on the surface has not turned into amorphous form as would be expected due to its constant irradiation by cosmic rays.

See also

• Namaka, the other moon of Haumea

External links

• Brown's publication describing the discovery of HiШаблон:Okinaiaka
• Paper describing the composition of HiШаблон:Okinaiaka