Namaka (moon)
In this photo taken by the Hubble Space Telescope, Namaka is the faint spot near the bottom, directly below Haumea (center). | |
| Discovery | |
|---|---|
| Discovered by | |
| Discovery site | W. M. Keck Obs., Mauna Kea |
| Discovery date | 2005 |
| Designations | |
Designation | (136108) Haumea II |
| Pronunciation | /nɑːˈmɑːkə/ Hawaiian: [naːˈmɐkə] |
Named after | Nāmaka |
| S/2005 (2003 EL61) 2 S/2005 (136108) 2 | |
| Orbital characteristics | |
| Epoch 28 May 2008 12:00 UT (JD 2454615.0) | |
| 25506±36 km | |
| Eccentricity | 0.2179+0.0033 −0.0032 |
| 18.2783±0.0076 d | |
| 185.19°+0.69° −0.65° | |
| Inclination |
|
| 23.725°+0.149° −0.150° (to ecliptic) | |
| 118.35°+0.39° −0.42° | |
| Satellite of | Haumea |
| Physical characteristics | |
| 150±50 km ≥ 83±2 km (occultation) | |
| Mass | (1.18±0.25)×1018 kg |
Mean density | ~0.65 g/cm3 (for 150 km diameter) |
| unknown, likely chaotic | |
| unknown, likely chaotic | |
| Albedo | 0.5 to 0.8 |
| Temperature | ≈40 K (same as Haumea) |
| ~22 | |
| 5.1 | |
Namaka (full designation (136108) Haumea II) is the smaller, inner moon of the trans-Neptunian dwarf planet Haumea. Discovered by Michael E. Brown and the Keck Observatory adaptive optics team in the fall of 2005, it is named after Nāmaka, a water spirit and one of the daughters of Haumea in Hawaiian mythology. Namaka follows a highly elliptical orbit that is highly tilted by roughly 13 degrees with respect to Haumea's equator. Namaka is heavily perturbed by both the gravitational influence of Haumea's larger, outer moon Hiʻiaka and the variable gravitational field of Haumea's elongated shape.
With a diameter of around 150 km (93 mi), Namaka is predicted to have an irregular shape and a chaotic rotation. It has a reflective surface made of fresh water ice, similar to that of Haumea and Hiʻiaka. Like Hiʻiaka, Namaka is believed to be a fragment of Haumea that was ejected in the aftermath of a giant impact 4.4 billion years ago.