< S

S/2020 S 4

S/2020 S 4
Discovery 
Discovered byEdward Ashton, Brett J. Gladman
Discovery date2020
Orbital characteristics[1]
Semi-major axis
18,235,500 km (11,331,000 mi)
Eccentricity0.495
2.538 yrs (926.96 d)
Inclination40.1° (to the ecliptic)
Satellite ofSaturn
GroupGallic group
Physical characteristics
Mean diameter
3 km
17.0

    S/2020 S 4 is a small and very faint natural satellite of Saturn. It was discovered by Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on June 24, 2020, and was announced on May 6, 2023 by the IAU Minor Planet Center after observations were collected over a long period of time to confirm the satellite's orbit that were taken between July 1, 2019 and July 9, 2021.[2]

    Orbit

    S/2020 S 4 is a highly eccentric satellite with an eccentricity of 0.495, it orbits Saturn at an average distance of 18.2 million km and an orbital period of 2 and a half years, with an inclination of 40.1° to the ecliptic, suggesting that it belongs to the Gallic group.[1] However, sometimes its moon group is disputed, and it may be included in the Inuit group.[3][4] It has been suggested that it was a fragment piece of Siarnaq that broke off a long time ago in a time-span of a few thousand years.[3]

    The orbit of S/2020 S 4 is liberating in accordance of von Zeipel–Lidov–Kozai effect.[5]

    Physical characteristics

    S/2020 S 4 is estimated to be 3 km in diameter and has an absolute magnitude of 17, making it one of the faintest moons of Saturn.[1] Scott S. Sheppard and Tilmann Denk on the other hand, estimated it to be 2 km and 2 and a quarter km, respectively.[4][3] If these estimates were true, it would make S/2020 S 4 one of the smallest known irregular moons of Saturn.[3]

    References

    1. 1 2 3 "Planetary Satellite Mean Elements". Jet Propulsion Laboratory. California Institute of Technology. Retrieved 6 May 2023.
    2. ↑ "MPEC 2023-J38 : S/2020 S 4". Minor Planet Electronic Circular. Minor Planet Center. Retrieved 6 May 2023.
    3. 1 2 3 4 "S/2020 S 4". Tilmann's Website. Tilmann Denk. Retrieved 23 March 2024.
    4. 1 2 "Saturn Moons". Carnegie Science. Earth & Planets Laboratory. Retrieved 23 March 2024.
    5. ↑ Grishin, Evgeni (September 2024). "Irregular Fixation II: The orbits of irregular satellites". Monthly Notices of the Royal Astronomical Society. 533 (1): 497–509. arXiv:2407.05123. Bibcode:2024MNRAS.533..497G. doi:10.1093/mnras/stae1752.
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