Saturn's Inuit group of satellites
The Inuit group is a dynamical grouping of the prograde irregular satellites of Saturn which follow similar orbits. Their semi-major axes range between 11 and 18 Gm, their inclinations between 40° and 50°, and their eccentricities between 0.15 and 0.48. They take about 2 years to orbit Saturn.
The group appeared quite homogeneous in early observations, the satellites displaying light-red colour (colour indices B−V = 0.79 and V−R = 0.51, similar to that of the Gallic group) and similar infrared spectra. Recent observations, however, revealed that Ijiraq is distinctly redder than Paaliaq, Siarnaq and Kiviuq. In addition, unlike the other three, Ijiraq's spectrum does not display weak absorption near 0.7 μm. This feature is attributed to a possible water hydration.
The spectral homogeneity (with the exception of Ijiraq) is consistent with a common origin in the break-up of a single object but the dispersion of the orbital parameters requires further explanation. Recently reported secular resonances among the members could provide the explanation of the post-collisional dispersion.
The known members of the group are (in order of increasing distance from Saturn):
- Grav, Tommy; Holman, Matthew J.; Gladman, Brett J.; Aksnes, Kaare Photometric survey of the irregular satellites, Icarus, 166,(2003), pp. 33–45. Preprint
- Tommy Grav and Matthew J. Holman Near-Infrared Photometry of the Irregular Satellites of Jupiter and Saturn,The Astrophysical Journal, 605, (2004), pp. L141–L144 Preprint
- Tommy Grav and James Bauer A deeper look at the colors of Saturnian irregular satellites, Preprint
Mean orbital parameters: from JPL