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S/2002 N 5

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S/2002 N 5
S/2002 N 5 imaged by theVery Large Telescopein September 2002
Discovery[1][2]
Discovered byMatthew Holman
John J. Kavelaars
Tommy Grav
Wesley Fraser
Discovery siteCerro Tololo Obs.
Discovery date14 August 2002
Designations
c02N4[3]
Orbital characteristics[4]
Epoch1 January 2020 (JD2458849.5)
Observation arc21.22yr(7,752d)
Satellite ofNeptune
GroupSaogroup
Proper orbital elements
23,414,700 km (0.156518AU)AU
0.433
46.3° (toecliptic)
41.6561611deg/yr
8.64218yr
(3156.556d)
Precession ofperihelion
451.707549arcsec/yr
Precession of theascending node
415.317659arcsec/yr
Physical characteristics
24–38 km[a]
23 km[5][6]
25.9 (average)[5]
11.2[1]

S/2002 N 5is a progradeirregular satelliteofNeptune.It was discovered on 14 August 2002 byMatthew Holman,John J. Kavelaars,Tommy Grav, and Wesley Fraser using the 4.0-meterVíctor M. Blanco TelescopeatCerro Tololo Observatory,Chile,but it becamelostand was not observed again untilScott S. Sheppardrediscovered it on 3 September 2021. The discovery of S/2002 N 5 was announced on 23 February 2024, after observations were collected over a long enough time to confirm the satellite's orbit.[1]S/2002 N 5 orbits Neptune at an average distance of over 23 million km (14 million mi) and takes almost 9 Earth years to complete its orbit.

Discovery[edit]

S/2002 N 5 was first observed on 14 August 2002 by Matthew Holman and collaborators, during their search for Neptunian irregular moons using the 4.0-mVíctor M. Blanco TelescopeatCerro Tololo Observatory,Chile.[3]: 866 Holman's team was able to detect this faint moon through theshift-and-add technique,in which they took many long-exposuretelescope images, aligned and shifted them to follow Neptune's motion, and then added them together to create a single deep image that would show Neptunian moons as points of light against trailed background stars and galaxies.[3]: 865 The moon was given the temporary designation "c02N4" and was among the faintest of the five Neptunian moons that Holman's team discovered in their search, which includedHalimede,Sao,Laomedeia,andNeso.[3]: 866 While four of these moons were successfully reobserved and subsequently announced, S/2002 N 5 was only reobserved once on 3 September 2002 by the 8.2-mVery Large TelescopeatEuropean Southern Observatory.[1][3]: 866 Further attempts to reobserve S/2002 N 5 were unsuccessful.[3]: 866 With very few observations, S/2002 N 5's orbit could not be confirmed and it became alostmoon.[3]: 866 [6]

S/2002 N 5 remained unobserved for 19 years since its last observation by Holman's team in September 2002.[1]On 3 September 2021,Scott S. Sheppardrediscovered S/2002 N 5 while searching for Neptunian irregular moons with the 6.5-mMagellan–Baade TelescopeatLas Campanas Observatory,Chile.[1][6]Like Holman's team, Sheppard used the shift-and-add technique to detect S/2002 N 5.[6]From September 2021 to November 2023, Sheppard and his collaboratorsDavid J. Tholen,Chad Trujillo,and Patryk S. Lykawka conducted follow-up observations of S/2002 N 5 using the Magellan–Baade Telescope and the 8.2-mSubaru TelescopeatMauna Kea, Hawaiito determine the moon's orbit and ensure it would not be lost.[1][6]After Sheppard's follow-up observations concluded, his team was able to link the moon back to its original discovery observations from 2002.[6]S/2002 N 5 andS/2021 N 1,another Neptunian irregular moon discovered by Sheppard's team, were both confirmed and announced by theMinor Planet Centeron 23 February 2024, bringing Neptune's number of known moons from 14 to 16.[1]

Orbit[edit]

Irregular satellites of Jupiter (red), Saturn (green), Uranus (magenta) and Neptune (blue; including Triton), plotted by distance from their planet (semi-major axis) in the horizontal axis andorbital inclinationin the vertical axis. The semi-major axis values are expressed as a fraction of the planet'sHill sphere's radius, while the inclination is expressed indegreesfrom theecliptic.The relative sizes of moons are indicated by the size of their symbols, and the Sao and Neso groups of Neptunian moons are labeled. Data as of February 2024.

S/2002 N 5 is anirregular moonof Neptune, since it has a distant, highlyelliptical,and highlyinclinedorbit. Irregular moons are loosely bound by Neptune's gravity because of their great distance from the planet, so their orbits are frequentlyperturbedby the gravity of the Sun and other planets.[7]: 2 This results in significant changes in the orbits of irregular moons over short periods of time, so a simpleKeplerian elliptical orbitcannot accurately describe the long-term orbital motions of irregular moons. Instead,proper or average orbital elementsare used to describe the long-term orbits of irregular moons more accurately, since these are calculated by averaging out the perturbed orbit over a long period of time.[7]: 4 

Over an 800-year time span from 1600 to 2400, S/2002 N 5's averagesemi-major axisor orbital distance from Neptune is 23.4 million km (14.5 million mi; 0.156 AU), with an averageorbital periodof 8.6Earth years.[4]S/2002 N 5 has an averageorbital eccentricityof 0.43 and an averageinclinationof 46.3° with respect to theecliptic,or the plane of Earth's orbit.[4]Since S/2002 N 5's orbital inclination is less than 90°, the moon has aprograde orbit,meaning it orbits in the same direction as Neptune's orbit around the Sun.[5]Due to perturbations, S/2002 N 5's orbital elements fluctuate over time: its semi-major axis can range from 23.3 to 23.6 million km (14.5 to 14.7 million mi), eccentricity from 0.24 to 0.67, and inclination from 37° to 50°.[8]S/2002 N 5's orbit exhibitsnodal precessionwith an average period of about 3,100 Earth years andapsidal precessionwith an average period of about 2,900 Earth years.[4]

S/2002 N 5 is part of the Sao group, a cluster of distant prograde irregular moons of Neptune that includesLaomedeiaand the group's namesakeSao.[5]The moons of the Sao group have orbital elements that are clustered with semi-major axes between 22–24 million km (14–15 million mi), eccentricities between 0.3 and 0.5, and inclinations between 30° and 50°.[5]Like all other irregular moon groups, the Sao group is thought to have formed from the destruction of a larger captured moon of Neptune due to asteroid and cometimpacts,which left many fragments in similar orbits around Neptune.[6]

Physical characteristics[edit]

S/2002 N 5 is very faint with an averageapparent magnitudeof 25.9, so it could only be observed with long-exposure imaging by large-aperturetelescopes like the Subaru Telescope.[5][6]Nothing is known about S/2002 N 5's physical properties other than itsabsolute magnitudeof 11.2, which can be used to estimate the moon's diameter.[1]Assuming ageometric albedorange of 0.04–0.10 that is typical for most irregular moons,[9]S/2002 N 5 has a diameter between 24–38 km (15–24 mi).[a]Sheppard estimates the diameter to be 23 km, which if correct would make S/2002 N 5 one of the smallest known satellite orbiting Neptune.[5][6]

Notes[edit]

  1. ^abThe diameter (in km) is calculated fromabsolute magnitude(H) andgeometric albedo(p) according to the formula.[10]Given H = 11.2 and assuming an albedo range of 0.04–0.10, the diameter range is24–38 km.

References[edit]

  1. ^abcdefghi"MPEC 2024-D114: S/2002 N 5".Minor Planet Electronic Circulars.Minor Planet Center. 23 February 2024.Retrieved23 February2024.
  2. ^"Planetary Satellite Discovery Circumstances".JPL Solar System Dynamics.NASA.Retrieved23 February2024.
  3. ^abcdefgHolman, Matthew; Kavelaars, J. J.; Grav, Tommy; Gladman, Brett J.; Fraser, Wesley C.; Milisavljevic, Dan (August 2004)."Discovery of five irregular moons of Neptune"(PDF).Nature.430(7002): 865–867.Bibcode:2004Natur.430..865H.doi:10.1038/nature02832.PMID15318214.S2CID4412380.
  4. ^abcd"Planetary Satellite Mean Elements".JPL Solar System Dynamics.NASA.Retrieved28 February2024.
  5. ^abcdefgSheppard, Scott S."Moons of Neptune".Earth & Planets Laboratory.Carnegie Institution for Science.Retrieved23 February2024.
  6. ^abcdefghi"New Uranus and Neptune Moons".Earth & Planetary Laboratory.Carnegie Institution for Science. 23 February 2024.Retrieved23 February2024.
  7. ^abBrozović, Marina; Jacobson, Robert A. (May 2022)."Orbits of the Irregular Satellites of Uranus and Neptune".The Astronomical Journal.163(5): 12.Bibcode:2022AJ....163..241B.doi:10.3847/1538-3881/ac617f.S2CID248458067.241.
  8. ^"JPL Horizons On-Line Ephemeris for 2002N5 Osculating Orbit (1600-Feb-01 to 2399-Dec-01)".JPL Horizons On-Line Ephemeris System.Jet Propulsion Laboratory.Retrieved1 March2024.Ephemeris Type: Elements. Center: 500@8 (Neptune Barycenter).
  9. ^Sharkey, Benjamin N. L.; Reddy, Vishnu; Kuhn, Olga; Sanchez, Juan A.; Bottke, William F. (November 2023)."Spectroscopic Links among Giant Planet Irregular Satellites and Trojans".The Planetary Science Journal.4(11): 20.arXiv:2310.19934.Bibcode:2023PSJ.....4..223S.doi:10.3847/PSJ/ad0845.S2CID264819644.223.
  10. ^"Asteroid Size Estimator".Center for Near Earth Object Studies.NASA.Retrieved23 February2024.

External links[edit]

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