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{{DISPLAYTITLE:Hi{{okina}}iaka (moon)}} |
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{{Infobox planet |
{{Infobox planet |
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| name = Hi{{okina}}iaka |
| name = Hi{{okina}}iaka |
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| caption = Hi{{okina}}iaka is above Haumea (center) in this [[Keck telescope]] image. |
| caption = Hi{{okina}}iaka is above Haumea (center) in this [[Keck telescope]] image. |
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| discovery = yes |
| discovery = yes |
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| discoverer = [[Michael E. Brown]], <br |
| discoverer = [[Michael E. Brown]], <br> [[Chad Trujillo]], <br> [[David Rabinowitz]], ''et al.'' |
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| discovered = 26 January 2005 |
| discovered = 26 January 2005 |
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| mp_name = Haumea I Hi{{okina}}iaka |
| mp_name = Haumea I Hi{{okina}}iaka |
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| alt_names = {{mp|(136108) 2003 EL|61}} I, <br |
| alt_names = {{mp|(136108) 2003 EL|61}} I, <br>{{mp|S|2005|2003 EL|61|1}} |
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| pronounce = {{IPA-en|ˌhiːʔiˈɑːkə|}},<ref name= |
| pronounce = {{IPA-en|ˌhiːʔiˈɑːkə|}},<ref name=dict-def/> or as in [[Hawaiian language|Hawaiian]] {{IPA-haw|ˈhiʔiˈjɐkə|}} |
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| orbit_ref = <ref name= |
| orbit_ref = <ref name=RagozzineBrown2009/> |
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| semimajor = {{val|49880|198|ul=km}} |
| semimajor = {{val|49880|198|ul=km}} |
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| eccentricity = {{val|0.0513|0.0078}} |
| eccentricity = {{val|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 = {{val|p=~|170|u=km}}<ref name= |
| mean_radius = {{val|p=~|170|u=km}}<ref name=Dumas2011/> |
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| mass = {{val|1.79|0.11|e=19|ul=kg}}<ref name= |
| mass = {{val|1.79|0.11|e=19|ul=kg}}<ref name=RagozzineBrown2009/>(0.45% of Haumea) |
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| density = {{val|p=~|1|ul=g/cm3}} |
| density = {{val|p=~|1|ul=g/cm3}} |
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| single_temperature = {{val|32|3|ul=K}} |
| single_temperature = {{val|32|3|ul=K}} |
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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 {{val|49.12|0.03|u=days}} at a distance of {{val|49880|198|ul=km}}, with an eccentricity of {{val|0.0513|0.0078}} and an inclination of {{val|126.356|0.064|s=°}}. Mutual events expected in July 2009 should improve the knowledge of the orbits and masses of the components of the Haumean system.<ref name=RagozzineBrown2009/> |
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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 {{val|49.12|0.03|u=days}} at a distance of {{val|49880|198|ul=km}}, with an eccentricity of {{val|0.0513|0.0078}} and an inclination of {{val|126.356|0.064|s=°}}. Mutual events expected in July 2009 should improve the knowledge of the orbits and masses of the components of the Haumean system.<ref name= |
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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 {{val|5.9|0.5|s=%}}, translating into the diameter about 22% of its primary, or in the range of {{val|350|u=km}}, assuming similar albedo.<ref name=RagozzineBrown2009/> 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 Hiʻiaka is is in hydrostatic equilibrium, i.e. rounded by its own gravity. However, it is not a dwarf-planet candidate because it is a moon. |
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⚫ |
Its measured brightness is {{val|5.9|0.5|s=%}}, translating into the diameter about 22% of its primary, or in the range of {{val|350|u=km}}, assuming similar albedo.<ref name= |
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=== Mass === |
=== Mass === |
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⚫ | The mass of Hi{{okina}}iaka is estimated to be {{val|1.79|0.11|e=19|ul=kg}} using precise relative [[astrometry]] from [[Hubble Telescope]] and [[Keck Telescope]] and applying [[3-body problem|3-body]], point-mass model to the Haumean system.<ref name=RagozzineBrown2009/> |
||
⚫ |
The mass of Hi{{okina}}iaka is estimated to be {{val|1.79|0.11|e=19|ul=kg}} using precise relative [[astrometry]] from [[Hubble Telescope]] and [[Keck Telescope]] and applying [[3-body problem|3-body]], point-mass model to the Haumean system.<ref name= |
||
=== Spectrum and composition === |
=== Spectrum and composition === |
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⚫ | The near infrared spectrum of Hiʻiaka 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 {{val|1.65|u=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 [[amorphous]] form as would be expected due to its constant irradiation by [[cosmic ray]]s.<ref name=Dumas2011/> |
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⚫ |
The near infrared spectrum of Hiʻiaka 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 {{val|1.65|u=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 [[amorphous]] form as would be expected due to its constant irradiation by [[cosmic ray]]s.<ref name= |
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== See also == |
== See also == |
File:2003 EL61 Haumea, with moons.jpg
Hiʻiaka is above Haumea (center) in this Keck telescope image.
| |
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] | |
49880±198 km | |
Eccentricity | 0.0513±0.0078 |
49.12±0.03 d | |
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 d at a distance of 49880±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 components of the Haumean 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 Hiʻiaka is is in hydrostatic equilibrium, i.e. rounded by its own gravity. However, it is not a dwarf-planet candidate because 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 Haumean system.[2]
The near infrared spectrum of Hiʻiaka 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 amorphous form as would be expected due to its constant irradiation by cosmic rays.[3]
|doi= 10.1088/0004-6256/137/6/4766
instead.
|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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Dwarf planets (moons) |
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