Neso
Neso imaged by the Very Large Telescope's FORS1 imager in September 2002
Discovery[1][2]
Discovered by
Discovery siteCerro Tololo Obs.
Discovery date14 August 2002
Designations
Designation
Neptune XIII
Pronunciation/ˈniːsoʊ/
Named after
Νησώ Nēsō
S/2002 N 4
AdjectivesNesoan /nɪˈsoʊ.ən/ or Nesoian /nɪˈsoʊ.iən/
Orbital characteristics[3]
Epoch 10 June 2003
Observation arc19.96 yr (7,292 days)[4]
Periapsis~21,215,700 km (0.141 AU)
Apoapsis~77,784,500 km (0.518 AU)
0.33 AU (~49,500,000 km), 3,220 Neptune radii, 49.285 Gm
Eccentricity0.5714
9740.73 d
(26.67 y)
Inclination136.439°
Satellite ofNeptune
Physical characteristics
Mean diameter
60 km (for albedo 0.04)[5]
Albedo0.04 (assumed)[5]
Spectral type
V–R = 0.58±0.13[6]
V–I = 1.0±0.4[7]
R–I = 0.7±0.4[7]
25.6±0.3 (V-band)[7]
10.67[4]

    Neso /ˈniːsoʊ/, also known as Neptune XIII, is the outermost known natural satellite of Neptune. It is a retrograde irregular moon discovered by Matthew J. Holman, Brett J. Gladman, et al. on 14 August 2002, though it went unnoticed until 2003.[2][8] Neso orbits Neptune at a distance of more than 48 Gm (billion m), making it (as of 2015) the most distant known moon of any planet. At apocenter, the satellite is more than 72 Gm from Neptune. This distance exceeds Mercury's aphelion, which is approximately 70 Gm from the Sun.

    Irregular satellites of Neptune

    Neso is also the moon with the longest orbital period, 26.67 years. It follows a retrograde, 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 (37 mi) in diameter based on an assumed albedo.

    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.[5]

    Neso is named after one of the Nereids. Before it was officially named on 3 February 2007 (IAUC 8802), Neso was known by its provisional designation, S/2002 N 4.

    See also

    References

    1. ↑ JPL (21 July 2011). "Planetary Satellite Discovery Circumstances". Jet Propulsion Laboratory. Retrieved 24 October 2011.
    2. 1 2 Green, Daniel W. E. (1 October 2003). "S/2001 U 2 and S/2002 N 4". IAU Circular. 8213. Retrieved 24 October 2011.
    3. ↑ Jacobson, R. A. (2008). "NEP078 – JPL satellite ephemeris". Planetary Satellite Mean Orbital Parameters. Retrieved 23 September 2009.
    4. 1 2 "Natural Satellites Ephemeris Service". Minor Planet Center. Retrieved 14 June 2023. Selection of Objects → "All Neptunian outer irregular satellites" → Check "I require Orbital Elements" → Get Information
    5. 1 2 3 Sheppard, Scott S.; Jewitt, David C.; Kleyna, Jan (2006). "A Survey for "Normal" Irregular Satellites around Neptune: Limits to Completeness". The Astronomical Journal. 132 (1): 171–176. arXiv:astro-ph/0604552. Bibcode:2006AJ....132..171S. doi:10.1086/504799. S2CID 154011.
    6. ↑ Graykowski, Ariel; Jewitt, David (April 2018). "Colors and Shapes of the Irregular Planetary Satellites". The Astronomical Journal. 155 (4): 10. arXiv:1803.01907. Bibcode:2018AJ....155..184G. doi:10.3847/1538-3881/aab49b. 184.
    7. 1 2 3 Maris, Michele; Carraro, Giovanni; Melita, Mario; Parisi, Gabriela (March 2018). "Multicolor Photometry of the Neptune Irregular Satellite Neso". Research Notes of the American Astronomical Society. 2 (1). arXiv:1803.07957. Bibcode:2018RNAAS...2...42M. doi:10.3847/2515-5172/aab7fc. 42.
    8. ↑ Holman, M. J.; Kavelaars, J. J.; Grav, T.; et al. (2004). "Discovery of five irregular moons of Neptune" (PDF). Nature. 430 (7002): 865–867. Bibcode:2004Natur.430..865H. doi:10.1038/nature02832. PMID 15318214. S2CID 4412380. Retrieved 24 October 2011.
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