Hiʻiaka (moon)
| Hi'iaka | |
|---|---|
 |
|
| Fantasy representation of Haumea, Hi'iaka and Namaka | |
| Provisional or systematic name | S / 2005 (2003 EL 61 ) 1 (136108) Haumea I |
| Central body | Haumea |
| Properties of the orbit | |
| Major semi-axis | 49,880 ± 198 km |
| Periapsis | 47,321 km |
| Apoapsis | 52,439 km |
| eccentricity | 0.0513 ± 0.0078 |
| Orbit inclination | 126.356 ° ± 0.064 °
(13.41 ± 0.08 ° to Namaka) ° |
| Orbital time | 49.462 ± 0.083 d |
| Mean orbital velocity | 13.6 km / s |
| Physical Properties | |
| Albedo | ~ 0.80 ± 0.07 |
| Medium diameter | ~ 320 km |
| Dimensions | ≈ 1.79 ± 0.11 ∙ 10 19 kg |
| Medium density | 1 ± 0.5 g / cm 3 |
| Acceleration of gravity on the surface | ≈ 0 m / s 2 |
| Escape speed | ≈ 0 m / s |
| Surface temperature | −241 ° C / 32 ± 3 K |
| discovery | |
| Explorer |
Team of the |
| Date of discovery | January 28, 2005 |
Hiʻiaka is the outer and larger moon of the dwarf planet Haumea . Its mean diameter is about 310 kilometers, which is about 1/5 the (mean) diameter of Haumea.
Discovery and naming
Hiʻiaka was discovered on January 28, 2005 by a team during observations from January 26 to 30 at the Keck Observatory on Mauna Kea , Hawaii . The team of discovery provisionally suggested the name Rudolph , the name of Santa's most famous reindeer in a popular US Christmas carol. The moon was given the provisional designation S / 2005 (2003 EL 61 ) 1 .
On September 17th, 2008 the moon was named after Hi'iaka , the Hawaiian goddess who is said to have been born from the mouth of Haumea . Hi'iaka is the goddess of dance and patroness of the big island of Hawaii.
Track properties
The companion circles Haumea in a progressive , slightly elliptical orbit between 47,321 and 52,439 km from its center (major orbit half-axis 49,880 km or an estimated 45 Haumea equator radii). The orbital eccentricity is 0.0513, the web is 126.356 ° relative to the ecliptic inclined . In addition, the orbit is tilted by about 13 ° compared to the second moon Namaka (40 ° according to previous calculations).
Hi'iaka may be responsible for the unusually high eccentricity of the inner moon Namaka, which is caused by disturbances due to resonances . They are currently in an approximately 8: 3 resonance. It is believed that the tidal forces move both moons outward.
Hi'iaka orbits Haumea in 49 days, 11 hours and 5.3 minutes, which corresponds to around 2091.9 orbits in one Haumea year (around 283.28 earth years).
Physical Properties
Hiʻiaka has an estimated 320 km in diameter based on the assumed reflectivity of 80%. The surface is therefore very light. Like Namaka, its density is estimated at 1.0 ± 0.5 g / cm 3 . Strong absorption at wavelengths of 1.2 and 2 micrometers in the infrared spectrum indicates that the surface is mainly composed of water ice . The mean surface temperature of Namaka is estimated to be −241 ° C (32 K ).
The mass of Hi'iaka is estimated to be 1.79 ∙ 10 19 kg today, assuming the same density and albedo as Haumea, i.e. a mass of about 0.45 percent of that of the central body.
It is possible that Hi'iaka was formed from material from an impact from another body in Haumea.
exploration
Since its discovery in 2005, Hi'iaka could only be observed through earth-based telescopes and its orbital elements could be determined.
In 1999 from the Earth seen a cover of the moon through its central body, this will happen again until the year 2138th
See also
Individual evidence
- ↑ Consisting of Antonin H. Bouchez, Michael E. Brown , Randall D. Campbell, Jason C. Chin, Marcos A. van Dam, Scott K. Hartman, Erik M. Johansson, Robert E. Lafon, David Le Mignant, Paul J. Stomski Jr., Douglas M. Summers, Peter L. Wizinowich, Chad Trujillo, and David Lincoln Rabinowitz .
Web links
- Wm. Robert Johnston: (136108) Haumea, Hi'iaka, and Namaka
- International Astronomical Union Circular No. 8577 July 29, 2005 (Discovery)
- International Astronomical Union Circular No. 8976 September 17, 2008 (designation)