Psamathe (moon)

Psamathe
Discovery images of Psamathe by the Subaru Telescope in 2003
Discovery[1][2]
Discovered by
Discovery date19 August 2003
Designations
Designation
Neptune X
Pronunciation/ˈsæməθiː/
Named after
Ψαμάθη Psamathē
S/2003 N 1
AdjectivesPsamathean /sæməˈθiːən/
Orbital characteristics
Epoch 1 January 2000 (Proper orbital element)
Observation arc20.97 yr (7,660 days)[3]
183.3° (proper)
Satellite ofNeptune
GroupNeso group
Proper orbital elements[4]
47,615,100 km = 0.318 AU
0.414
127.8°
14.371255 deg / yr
25.05 yr
(9149.514 d)
Precession of perihelion
874.6486 arcsec / yr
Precession of the ascending node
972.3189 arcsec / yr
Physical characteristics
40 km (for albedo 0.04)[5]
Albedo0.04 (assumed)[5]

Psamathe /ˈsæməθiː/, also known as Neptune X, is a retrograde irregular satellite of Neptune. It is named after Psamathe, one of the Nereids. Psamathe was discovered by Scott S. Sheppard and David C. Jewitt in 2003 using the 8.2 meter Subaru Telescope.[5] Before it was officially named on February 3, 2007 (IAUC 8802), it was known by the provisional designation S/2003 N 1.[6]

Animation of Psamathe moving in images by Very Large Telescope on 13 July 2010

Psamathe is about 38 kilometers in diameter. It orbits Neptune at a distance of between 25.7 and 67.7 million km (for comparison, the Sun-Mercury distance varies between 46 million and 69.8 million km) and requires almost 25 Earth years to make one orbit. The orbit of this satellite is close to the theoretical stable separation from Neptune for a body in a retrograde orbit. Given the similarity of Psamathe's orbital parameters with Neso (S/2002 N 4), it was suggested that both irregular satellites could have a common origin in the breakup of a larger moon.[5] Both are farther from their primary than any other known moon in the Solar System.[7]

  1. ^ Cite error: The named reference JPL-Discoverers was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference IAUC 8193 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference MPC-NatSats was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference JPL-Jacobson2008 was invoked but never defined (see the help page).
  5. ^ a b c d Cite error: The named reference SheppardJewittKleyna2006 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Marsden2003 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Schmude2008 was invoked but never defined (see the help page).