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| alt_names = (136108) 2003 EL61 I,<br> S/2005 ({{mp|2003 EL|61}}) 1 |
| alt_names = (136108) 2003 EL61 I,<br> S/2005 ({{mp|2003 EL|61}}) 1 |
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| pronounce = {{IPA-en|ˌhiːʔiˈɑːkə|}},<ref>In US dictionary transcription, {{USdict|hē′·-ē·â′·kə}}.</ref> or as in [[Hawaiian language|Hawaiian]] {{IPA-haw|ˈhiʔiˈjɐkə|}} |
| pronounce = {{IPA-en|ˌhiːʔiˈɑːkə|}},<ref>In US dictionary transcription, {{USdict|hē′·-ē·â′·kə}}.</ref> or as in [[Hawaiian language|Hawaiian]] {{IPA-haw|ˈhiʔiˈjɐkə|}} |
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| orbit_ref = <ref name="Brown2009"> |
| orbit_ref = <ref name="Ragozzine&Brown2009"/> |
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D. Ragozzine, [[Michael E. Brown|M. E. Brown]] ''Orbits And Masses Of The Satellites Of The Dwarf Planet Haumea = 2003 EL61'', To appear in The Astronomical Journal (2009) [http://arxiv.org/abs/0903.4213 Preprint on arXiv]</ref> |
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| semimajor = 49 880 ± 198 km |
| semimajor = 49 880 ± 198 km |
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| eccentricity = 0.0513 ± 0.0078 |
| eccentricity = 0.0513 ± 0.0078 |
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| satellite_of = {{dp|Haumea}} |
| satellite_of = {{dp|Haumea}} |
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| physical_characteristics = yes |
| physical_characteristics = yes |
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| mean_radius = ~ |
| mean_radius = ~170km<ref name=Dumas2011/> |
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| mass = 1.79 ± 0.11{{e|19}} [[Kilogram|kg]]<ref name="Brown2009"/> |
| mass = 1.79 ± 0.11{{e|19}} [[Kilogram|kg]]<ref name="Ragozzine&Brown2009"/>(0.45% of Haumea) |
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| density = |
| density = ~1g/cm<sup>3</sup> |
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| single_temperature = 32 ± 3 [[Kelvin|K]] |
| single_temperature = 32 ± 3 [[Kelvin|K]] |
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| rotation = (unknown) |
| rotation = (unknown) |
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==Discovery and naming== |
==Discovery and naming== |
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Hi{{okina}}iaka was the first [[natural satellite|satellite]] discovered around Haumea. It is named after one of the daughters of [[Haumea (mythology)|Haumea]], [[Hiiaka|Hi{{okina}}iaka]], the patron goddess of the [[Big Island of Hawaii]], though at first it had gone by the nickname "[[Rudolph the Red-Nosed Reindeer|Rudolph]]" by its discovery team. It orbits once every 49.12 ± 0.03 days at a distance of 49,880 ± 198 km, with an eccentricity of 0.0513 ± 0.0078 and an inclination of 126.356 ± 0.064°. Mutual events expected in July 2009 should improve the knowledge of the orbits and masses of the Haumea system.<ref name="Brown2009"/> |
Hi{{okina}}iaka was the first [[natural satellite|satellite]] discovered around Haumea. It is named after one of the daughters of [[Haumea (mythology)|Haumea]], [[Hiiaka|Hi{{okina}}iaka]], the patron goddess of the [[Big Island of Hawaii]], though at first it had gone by the nickname "[[Rudolph the Red-Nosed Reindeer|Rudolph]]" by its discovery team. It orbits once every 49.12 ± 0.03 days at a distance of 49,880 ± 198 km, with an eccentricity of 0.0513 ± 0.0078 and an inclination of 126.356 ± 0.064°. Mutual events expected in July 2009 should improve the knowledge of the orbits and masses of the Haumea system.<ref name="Ragozzine&Brown2009"/> |
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==Physical characteristics== |
==Physical characteristics== |
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===Size and brightness=== |
===Size and brightness=== |
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Its measured brightness is 5.9 ± 0.5%, translating into the diameter about 22% of its primary, or in the range of 350 km, assuming similar albedo. To put this in perspective, this moon would be the [[List_of_notable_asteroids#Largest_known_asteroids_.28out_to_the_orbit_of_Jupiter.29|fifth largest]] (cis-neptunian) asteroid after [[1 Ceres]], [[2 Pallas]], [[4 Vesta]], and [[10 Hygiea]] if it were in the [[asteroid belt]]. Future exploration of Haumea and its moons could reveal that Hi'iaka is rounded by its own gravity, in other words is in hydrostatic equilibrium. However, it would not be a potential dwarf planet candidate because, like Namaka, it is a moon. |
Its measured brightness is 5.9 ± 0.5%, translating into the diameter about 22% of its primary, or in the range of 350 km, assuming similar albedo.<ref name="Ragozzine&Brown2009"/> To put this in perspective, this moon would be the [[List_of_notable_asteroids#Largest_known_asteroids_.28out_to_the_orbit_of_Jupiter.29|fifth largest]] (cis-neptunian) asteroid after [[1 Ceres]], [[2 Pallas]], [[4 Vesta]], and [[10 Hygiea]] if it were in the [[asteroid belt]]. Future exploration of Haumea and its moons could reveal that Hi'iaka is rounded by its own gravity, in other words is in hydrostatic equilibrium. However, it would not be a potential dwarf planet candidate because, like Namaka, it is a moon. |
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===Mass=== |
===Mass=== |
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The mass of Hi{{okina}}iaka is estimated to be 1.79 ± 0.11{{e|19}} [[Kilogram|kg]] |
The mass of Hi{{okina}}iaka is estimated to be 1.79 ± 0.11{{e|19}} [[Kilogram|kg]] using precise relative [[astrometry]] from [[Hubble Telescope]] and [[Keck Telescope]] and applying [[3-body problem|3-body]], point-mass model to the Haumea system.<ref name="Ragozzine&Brown2009"> |
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{{cite journal |
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|last=Ragozzine |
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|first=D. |
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|coauthors=Brown, M.E. |
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|year=2009 |
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|title=Orbits and Masses of the Satellites of the Dwarf Planet Haumea = 2003 EL61 |
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|journal=The Astronomical Journal |
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|id= |
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|arxiv=0903.4213|bibcode = 2009AJ....137.4766R |doi = 10.1088/0004-6256/137/6/4766 }} |
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</ref> |
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===Spectrum and composition=== |
===Spectrum and composition=== |
File:2003 EL61.jpg | |
Discovery | |
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Discovered by | Michael E. Brown, Chad Trujillo, David Rabinowitz, et al. |
Discovery date | 26 January 2005 |
Designations | |
Designation | Haumea I Hiʻiaka |
Pronunciation | /ˌhiːʔiˈɑːkə/,[1] or as in Hawaiian [ˈhiʔiˈjɐkə] |
(136108) 2003 EL61 I, S/2005 (2003 EL61) 1 | |
Orbital characteristics[2] | |
49 880 ± 198 km | |
Eccentricity | 0.0513 ± 0.0078 |
49.12 ± 0.03 days | |
Inclination | 126.356 ± 0.064° |
Satellite of | Haumea |
Physical characteristics | |
~170 km[3] | |
Mass | 1.79 ± 0.11×1019 kg[2](0.45% of Haumea) |
Mean density | ~ 1 g/cm3 |
(unknown) | |
(unknown) | |
Albedo | (unknown) |
Temperature | 32 ± 3 K |
3.3 difference from primary's 17.3 | |
Hiʻiaka is the larger, outer moon of the dwarf planet Haumea.
Hiʻiaka was the first satellite discovered around Haumea. It is named after one of the daughters of Haumea, Hiʻiaka, the patron goddess of the Big Island of Hawaii, though at first it had gone by the nickname "Rudolph" by its discovery team. It orbits once every 49.12 ± 0.03 days at a distance of 49,880 ± 198 km, with an eccentricity of 0.0513 ± 0.0078 and an inclination of 126.356 ± 0.064°. Mutual events expected in July 2009 should improve the knowledge of the orbits and masses of the Haumea system.[2]
Its measured brightness is 5.9 ± 0.5%, translating into the diameter about 22% of its primary, or in the range of 350 km, assuming similar albedo.[2] To put this in perspective, this moon would be the fifth largest (cis-neptunian) asteroid after 1 Ceres, 2 Pallas, 4 Vesta, and 10 Hygiea if it were in the asteroid belt. Future exploration of Haumea and its moons could reveal that Hi'iaka is rounded by its own gravity, in other words is in hydrostatic equilibrium. However, it would not be a potential dwarf planet candidate because, like Namaka, it is a moon.
The mass of Hiʻiaka is estimated to be 1.79 ± 0.11×1019 kg using precise relative astrometry from Hubble Telescope and Keck Telescope and applying 3-body, point-mass model to the Haumea system.[2]
The near infrared spectrum of Hi'iaka is dominated by water ice absorption bands, which means that the surface of this moon is made mainly of water ice. The presence of the band centered at 1.65 μm indicates that the ice is primarily in the crystalline form. Currently it is unclear why water ice on the surface has not turned into the amorphous form as would be expected due to its continues irradiation by cosmic rays.[3]
{{cite journal}}
: Unknown parameter |coauthors=
ignored (|author=
suggested) (help)
|doi=10.1051/0004-6361/201015011
instead.
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Moons and rings |
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Collisional family |
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Astronomy |
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TNO classes |
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Dwarf planets (moons) |
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Sednoids |
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