Siarnaq (moon)

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Siarnaq - Saturn XXIX
Discovery [1]
Discovered by Brett J. Gladman et al.
Discovered in 2000
Mean Orbital elements [2]
Epoch 2000 Feb. 26.00
Semi-major axis 17.531 Gm
Eccentricity 0.2961
Inclination 46.0° *
Orbital period 895.55 d
(2.45 yr)
Physical characteristics
Mean diameter 40 km[3] **
Rotation period ?
Albedo 0.04 [3] assumed
Color light red
B-V=0.87 R-V=0.48[4]
Spectral type ?
*to the ecliptic **based on the albedo
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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)
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 [8] [9][4].

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.

[edit] 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 2000 October 25 (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 2000 December 19 (discovery and ephemeris)
  7. ^ IAUC 8177: Satellites of Jupiter, Saturn, Uranus 2003 August 8 (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 (2001 July 12), 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

[edit] External links


v • d • e
Moons of Saturn
Generally listed in increasing distance from Saturn. Temporary names in italics.
Ring shepherds
Co-orbitals
Inner large (and Trojan)
Mimas · Methone · Anthe · Pallene · Enceladus · Tethys (Telesto • Calypso) · Dione (Helene • Polydeuces)
Outer large
Inuit group
Kiviuq · Ijiraq · Paaliaq · Siarnaq · Tarqeq
Norse group
Gallic group
Rings of Saturn · Cassini-Huygens · Themis · Chiron