Sao (moon)

Sao
Sao imaged by the Very Large Telescope's FORS1 imager in September 2002
Discovery[1][2]
Discovered by
Discovery dateAugust 14, 2002
Designations
Designation
Neptune XI
Pronunciation/ˈseɪ.oʊ/
Named after
Σαώ Saō
S/2002 N 2
AdjectivesSaonian /seɪˈoʊniən/[3]
Orbital characteristics[4]
Epoch June 10, 2003
22,228,000 km
Eccentricity0.1365
2912.72 days
(7.97 yr)
Inclination53.483°
Satellite ofNeptune
GroupSao group
Physical characteristics
44 km (for albedo 0.04)[5]
Albedo0.04 (assumed)[5]

Sao /ˈseɪ.oʊ/ is a prograde irregular satellite of Neptune. It was discovered by Matthew J. Holman et al. on August 14, 2002.[6]

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).[5]

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 Kozai resonance, i.e. its inclination and eccentricity are coupled (the inclination of the orbit decreases while eccentricity increases and vice versa).[6]

Sao, or Neptune XI, like many of the outer satellites of Neptune, is named after one of the Nereids; Sao was associated with sailing and is referred to as "The rescuer" or "Safety". Before the announcement of its name on February 3, 2007 (IAUC 8802), Sao was known provisionally as S/2002 N 2.

  1. ^ Cite error: The named reference JPL-Discoverers was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference IAUC 8047 was invoked but never defined (see the help page).
  3. ^ Cf. the etymology of Saonia[1]
  4. ^ Cite error: The named reference JPL-Jacobson2008 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference SheppardJewittKleyna2006 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference HolmanKavelaarsGrav2004 was invoked but never defined (see the help page).