Namaka (moon)

Namaka

Artist's impression of Haumea, Hi'iaka and Namaka
Provisional or systematic name	S / 2005 (2003 EL ₆₁ ) 2 (136108) Haumea II
Central body	(136108) Haumea
Properties of the orbit
Major semi-axis	(25,657 ± 91) km
Periapsis	19,268 km
Apoapsis	32,046 km
eccentricity	0.249 ± 0.015 (2009; variable )
Orbit inclination	113.013 ° ± 0.075 ° (13.41 ± 0.08 ° to Hi'iaka) °
Orbital time	(18.2783 ± 0.0076) d
Physical Properties
Albedo	≈ 0.8 ± 0.2
Medium diameter	160 km
Dimensions	≈ (1.79 ± 1.48) 10 ¹⁸ kg
Medium density	(1.0 ± 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	Keck Observatory team
Date of discovery	June 30, 2005
Remarks	Most eccentric orbit in relation to its proximity to the central body in the solar system.

Namaka is the inner and smaller moon of the dwarf planet Haumea . Its mean diameter is about 160 kilometers, which is about 1/10 of the (mean) diameter of Haumea.

Discovery and naming

Namaka was born on June 30, 2005 by a team consisting of Michael E. Brown , MA van Dam, AH Bouchez, D. Le Mignant, RD Campbell, JCY Chin, A. Conrad, SK Hartman, EM Johansson, RE Lafon, David Lincoln Rabinowitz, PJ Stomski, Jr., DM Summers, Chadwick A. Trujillo, and PL Wizinowich discovered during observations at the Keck Observatory on Mauna Kea in Hawaii . The team of discovery provisionally suggested speed cameras as the name . Blitzer is the name of Santa's reindeer . The discovery was announced on November 29, 2005; the moon was given the provisional designation S / 2005 (2003 EL ₆₁ ) 2.

On September 17th, 2008, the moon was named after Namaka , the Hawaiian water spirit, who, unlike his sister Hiʻiaka, is said to have been born from the body of Haumea .

Track properties

The tracks of Namaka (cyan) and Hi'iaka (blue)

The companion circles Haumea in a prograde , very elliptical orbit between 19,268 and 32,046 km from its center (major orbit half-axis 25,657 km or an estimated 23 Haumea equator radii). The orbital eccentricity is 0.249, the web is 113.013 ° relative to the ecliptic inclined .

The orbital eccentricity is extremely unusual, as the lunar systems in the solar system usually become more eccentric with increasing distance from the central body. Namaka also has the most eccentric orbit in relation to its proximity to the central body, which is possibly caused by disturbances due to resonances with the outer moon Hi'iaka . It is believed that the tidal forces move both moons outward. At the moment they are almost in an 8: 3 resonance. This disrupts Namaka's orbit, which is currently precessioning ~ 20 °. In addition, the orbit is tilted by about 13 ° compared to the second moon Hi'iaka .

Namaka orbits Haumea in 18 days 6 hours and 40.8 minutes, which corresponds to around 5660.7 orbits in a Haumea year (around 283.28 earth years).

At present the Haumea system can be seen from the earth roughly from the side, so that Namaka periodically obscures Haumea. This is useful for determining the shape and mass of Haumea more precisely through the slight changes in brightness.

Physical Properties

Artist's impression of Namaka

Namaka has an estimated 160 km in diameter based on an assumed reflectivity of 80%. The surface is very bright, the moon (4.6 ± 0.5) may be weaker than Haumea. Like Hi'iaka, its density is estimated to be (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 exact mass of Namaka is not known, but assuming the same density and albedo as Haumea, the mass is about 0.2% of that of the central body.

It is possible that Namaka was created from material from an impact from another body in Haumea.

exploration

Since its discovery in 2005, Namaka could only be observed through earth-based telescopes and its orbital elements could be determined.

Web links

Wm. Robert Johnston: (136108) Haumea, Hi'iaka, and Namaka
IAUC No. 8636 December 1, 2005 (discovery)
IAUC No. 8976 September 17, 2008 (designation)


earth	moon
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Uranus ( list )	Ariel • Belinda • Bianca • Caliban • Cordelia • Cressida • Cupid • Desdemona • Ferdinand • Francisco • Juliet • Mab • Margaret • Miranda • Oberon • Ophelia • Perdita • Portia • Prospero • Puck • Rosalind • Setebos • Stephano • Sycorax • Titania • Trinculo • Umbriel
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Haumea	Hi'iaka • Namaka
Makemake	S / 2015 (136472) 1
Eris	Dysnomia