Siarnaq

Siarnaq (pronounced /ˈsiːɑrnɑːk/ SEE-ar-naak, or Saturn XXIX, is a prograde irregular satellite of Saturn. It was discovered by Brett J. Gladman, et al. in 2000[5],[6] and given the temporary designation S/2000 S 3. Named in August 2003 after the giant Siarnaq[7] (also known as Sedna) in Inuit mythology, it is the largest member of the Inuit group of irregular satellites.
Irregular prograde groups of satellites of Saturn: Inuit (blue) and Gallic (red)

Siarnaq is thought to be about 40 kilometres in diameter and orbits Saturn at an average distance of 17.5 Gm in 895 days.

The diagram illustrates its orbit in relation to other prograde irregular satellites of Saturn. The eccentricity of the orbits is represented by the yellow segments extending from the pericentre to the apocentre.

Siarnaq displays light-red colours and the infrared spectrum very similar to Paaliaq and Kiviuq, supporting the thesis of a possible common origin in the break-up of a larger body [4] [8][9].

Siarnaq has been found to be in a secular resonance with Saturn, involving the precession of its periapsis and that of the planet.[10]1

The studies of these resonances are key to understand the capture mechanism for the irregular satellites and, assuming a common origin of a given dynamical group in the break-up of a single body, to explain today’s dispersion of the orbital elements.

1The ecliptic longitudes of the periapsis of the satellite and the planet are locked.

References

1. ^ Discovery Circumstances (JPL)
2. ^ Mean orbital parameters from JPL
3. ^ a b Scott Sheppard pages
4. ^ a b Grav, T.; and Bauer, J.; A deeper look at the colors of Saturnian irregular satellites
5. ^ IAUC 7513: S/2000 S 3 and S/2000 S 4 October 25, 2000 (discovery)
6. ^ MPEC 2000-Y14: S/2000 S 3, S/2000 S 4, S/2000 S 5, S/2000 S 6, S/2000 S 10 December 19, 2000 (discovery and ephemeris)
7. ^ IAUC 8177: Satellites of Jupiter, Saturn, Uranus August 8, 2003 (naming the moon)
8. ^ Gladman, B. J.; Nicholson, P. D.; Burns, J. A.; Kavelaars, J. J.; Marsden, B. G.; Holman, M. J.; Grav, T.; Hergenrother, C. W.; Petit, J.-M.; Jacobson, R. A.; and Gray, W. J.; Discovery of 12 satellites of Saturn exhibiting orbital clustering, Nature, 412 (July 12, 2001), pp. 163–166
9. ^ Grav, T.; Holman, M. J.; Gladman, B. J.; Aksnes, K.; Photometric survey of the irregular satellites, Icarus, 166 (2003), pp. 33-45
10. ^ Ćuk, M.; Burns, J. A.; On the Secular Behavior of Irregular Satellites, The Astronomical Journal, 128 (2004), pp. 2518-2541

* Ephemeris IAU-MPC NSES

External links

* David Jewitt pages
* Scott Sheppard pages