S/2004 S 4

S/2004 S 4 is the provisional designation of an unconfirmed object seen orbiting Saturn within the inner strand of the F ring on June 21, 2004. It was spotted while J. N. Spitale was trying to confirm the orbit of another provisional object, S/2004 S 3 that was seen 5 hours earlier just exterior to the F ring.[2] The announcement was made on September 9, 2004.[4]

S/2004 S 4
Discovery
Discovered byCICLOPS Team [1][2]
Discovery dateJune 21, 2004
Orbital characteristics [3]
~140,100 km
Eccentricityunknown, small
~0.618 d
Inclinationunknown, small
Satellite ofSaturn
GroupF Ring
Physical characteristics
Mean radius
~2 km
probably synchronous
unknown
Albedounknown

    Despite later attempts to recover it, it has not been reliably sighted since. Notably, an imaging sequence covering an entire orbital period at 4 km resolution taken on November 15, 2004 failed to recover the object. The sequence should have been easily capable of detecting a moon of similar size, suggesting it to simply be a transient clump. An approximate linkage could be made of S/2004 S 3 to S/2004 S 4, and matched to two other detected clumps on other dates, but considering its non-detection in November, their relation is probably coincidental.[5]

    An interpretation where S/2004 S 3 and S/2004 S 4 are or were a single object on a F-ring crossing orbit is also possible.[4] Such an object might also be orbiting at a slightly different inclination to the F ring, thereby not actually passing through the ring material despite being seen both radially inward and outward of it.

    If a solid object after all, S/2004 S 4 would be 3–5 km in diameter based on brightness.

    References

    Citations

    1. CICLOPS Team.
    2. Martinez, Ormrod & Finn 2004.
    3. PGJ Astronomie webpage (Gilbert Javaux) Note that the F ring is centered at ~140,180 km.
    4. IAUC 8401.
    5. Spitale Jacobson et al. 2006.

    Sources

    • "Cassini Imaging Science Team". Cassini Imaging Central Laboratory for OPerationS. Retrieved 2012-01-01.
    • Green, Daniel W. E. (September 9, 2004). "S/2004 S 3, S/2004 S 4, and R/2004 S 1" (discovery). IAU Circular. 8401. Retrieved 2012-01-01.
    • Martinez, Carolina; Ormrod, Gill; Finn, Heidi (September 9, 2004). "Cassini Discovers Ring and One, Possibly Two, Objects at Saturn". jpl.nasa.gov. NASA Jet Propulsion Laboratory. Retrieved 2012-01-01.
    • Spitale, J. N.; Jacobson, R. A.; Porco, C. C.; Owen, W. M., Jr. (2006). "The orbits of Saturn's small satellites derived from combined historic and Cassini imaging observations". The Astronomical Journal. 132 (2): 692–710. Bibcode:2006AJ....132..692S. doi:10.1086/505206.
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