Siarnaq (moon)
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| Discovery [1] | |
|---|---|
| Discovered by | Brett J. Gladman et al. |
| Discovered | in 2000 |
| Mean Orbital elements [2] | |
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| 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 | ? |
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| *to the ecliptic | **based on the albedo |
Siarnaq (see'-ar-naak, IPA: [ˈsiarnak]), or Saturn XXIX, is a prograde irregular satellite of Saturn. It was discovered by Brett J. Gladman, et al. in 2000, and given the temporary designation S/2000 S 3. Named after the giant Siarnaq (also known as Sedna) in Inuit mythology, it is the largest member of the Inuit group of irregular satellites.
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 [5] [6] [4].
Siarnaq has been found to be in a secular resonance with Saturn, involving the precession of its periapsis and that of the planet[7].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 longitudes of the periapsis of the satellite and the planet are locked.
[edit] External links
[edit] References
- ^ Discovery Circumstances (JPL)
- ^ Mean orbital parameters from JPL
- ^ a b Scott Sheppard pages
- ^ a b Tommy Grav and James Bauer A deeper look at the colors of Saturnian irregular satellites, Preprint
- ^ B. Gladman, P. Nicholson, Burns, JJ Kavelaars, Brian G. Marsden, Holman, Grav T. et al. Discovery of 12 satellites of Saturn exhibiting orbital clustering., Nature, 412 (2001), p. 163
- ^ Grav, Tommy; Holman; B. Gladman; Aksnes, Kaare Photometric survey of the irregular satellites, Icarus, 166,(2003), pp. 33-45. Preprint
- ^ Ćuk, Matija; Burns, Joseph A. On the Secular Behavior of Irregular Satellites, The Astronomical Journal, 128 (2004), pp. 2518-2541 Preprint
- Ephemeris from IAU
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Generally listed in increasing distance from Saturn
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| Ring shepherds | Pan · Daphnis · Atlas · Prometheus · S/2004 S 6? · S/2004 S 4? · S/2004 S 3? · Pandora |
| Co-orbitals | Epimetheus · Janus |
| Inner large and Trojan | Mimas · Methone · Pallene · Enceladus · Tethys (trojans Telesto, Calypso) · Dione (trojans Helene, Polydeuces) |
| Outer large | Rhea · Titan · Hyperion · Iapetus |
| Inuit group | Kiviuq · Ijiraq · Paaliaq · Siarnaq |
| Norse group | Phoebe · Skathi · Skoll · S/2004 S 13 · S/2006 S 4 · Hyrokkin · Mundilfari · S/2006 S 6 · S/2006 S 1 · S/2004 S 17 · Narvi · Bergelmir · Aegir · Suttungr · S/2004 S 12 · Bestla · Farbauti · Hati · S/2004 S 7 · Thrymr · S/2006 S 3 · Surtur · Kari · Fenrir · Ymir · Loge · Fornjot |
| Gallic group | Albiorix · Bebhionn · Erriapo · Tarvos |
