Sao (moon)

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Sao
Discovery [1]
Discovered by M.Holman
JJ Kavelaars
T. Grav, W. Fraser
D. Milisavljevic
Discovered August 14, 2002
Mean Orbital elements [2]
Epoch June 10, 2003
Semi-major axis 22.422 Gm
Eccentricity 0.2931
Inclination 48.511° *
Orbital period 2914.1 days
(7.98 yr)
Physical characteristics
Mean diameter 44 km[2] **
Rotation period  ?
Albedo 0.04 assumed[2]
Color  ?
Spectral type  ?
*to the ecliptic **based on the albedo

Sao is a prograde irregular satellite of Neptune. It was discovered by Matthew J. Holman et al. on August 14, 2002.[3]

Irregular satellites of Neptune.
Irregular satellites of Neptune.

Sao orbits Neptune at a distance of about 22.4 million km and is about 44 kilometers in diameter (assuming an albedo of 0.04).[2]

Sao follows an exceptionally inclined and moderately eccentric orbit illustrated on the diagram in relation to other irregular satellites of Neptune. The satellites above the horizontal axis are prograde, the satellites beneath it are retrograde. The yellow segments extend from the pericentre to the apocentre, showing the eccentricity.

The satellite is in so-called Kozai resonance, i.e. its inclination and eccentricity are coupled (the inclination of the orbit decreases while eccentricity increases and vice versa).[3]

Sao, or Neptune XI, like many of the outer satellites of Neptune, is named after one of the Nereids; Sao was assocated with sailing and is referred to as "The rescuer" or "Safety". Prior to January 29, 2007, Sao was known provisionally as S/2002 N 2.


[edit] See also

[edit] External links

[edit] References

  1. ^ Discovery Circumstances from JPL
  2. ^ a b c d S. Sheppard, D. Jewitt and J. Kleyna A Survey for "Normal" Irregular Satellites Around Neptune: Limits to Completeness, The Astronomical Journal, 132 (2006), pp. 171–176. Preprint.
  3. ^ a b M. Holman, JJ Kavelaars, B. Gladman, T. Grav, W. Fraser, D. Milisavljevic, P. Nicholson, J. Burns, V. Carruba, J.-M. Petit, P. Rousselot, O. Mousis, B. Marsden; R. Jacobson; Discovery of five irregular moons of Neptune, Nature, 430 (2004), pp. 865-867. Final preprint(pdf)
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