Neso (moon)

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Neso
Discovery [1]
Discovered by M. Holman et al.
B. Gladman et al.
Discovered August 14, 2002
Mean Orbital elements [2]
Epoch June 10, 2003
Semi-major axis 48.387 Gm
Eccentricity 0.4945
Inclination 132° *
Orbital period 9374.0 d
(25.7 a)
Physical characteristics
Mean diameter 60 km[2] **
Rotation period  ?
Albedo 0.04 assumed[2]
Color  ?
Spectral type  ?
*to the ecliptic **based on the albedo

Neso, also known as Neptune XIII, is the outermost irregular natural satellite of Neptune. It was discovered by Matthew J. Holman, Brett J. Gladman, et al. on August 14, 2002, though it went unnoticed until 2003.[3][4]

Irregular satellites of Neptune.
Irregular satellites of Neptune.

Neso orbits Neptune at a distance of more than 48 Gm (million km), making it the most distant known moon of any planet1. It follows a highly inclined and highly 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.

Neso is about 60 km in diameter, and assuming the mean density of 1.5 g/cm3[5] its mass is estimated at 1.6×1017 kg.

Given the similarity of the orbit's parameters with Psamathe (S/2003 N 1), it was suggested that both irregular satellites could have a common origin in the break-up of a larger moon..[2]

Neso is named after one of the Nereides. Prior to January 29, 2007, Neso was known by its provisional designation, S/2002 N 4.

1Such distances are of the order of magnitude of heliocentric distances of inner planets rather than moons; at apocenter the satellite is more than 72 Gm (72 million km) from the planet to compare with Mercury's aphelion of ~70 Gm!

[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. ^ IAU Circular 8213
  4. ^ 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)
  5. ^ Physical parameters from JPL
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