Astronomy:Saturn's Norse group of satellites

Short description: Category of satellites of Saturn

Irregular satellites of Saturn. The diagram illustrates the Norse group in relation to other irregular satellites of Saturn. The eccentricity of the orbits is represented by the yellow segments (extending from the pericentre to the apocentre) with the inclination represented on Y axis.

The Norse group is a large group of retrograde irregular satellites of Saturn. Their semi-major axes range between 12 and 24 Gm, their inclinations between 136° and 175° and their eccentricities between 0.13 and 0.77. Unlike for the Inuit and Gallic groups, the orbital parameters are widely dispersed and group is likely to be composed from a number of subgroups with more homogenous orbital and physical parameters. For example, the satellites with inclinations around 174 degrees alone are thought to comprise at least two subgroups. Eight other moons form the Skathi subgroup. Their semi-major axes range between 15 and 20 Gm, their inclinations between 147° and 158°. Narvi forms a separate subgroup with Bestla. The International Astronomical Union (IAU) reserves names taken from Norse mythology (mostly giants) for these moons. The exception is Phoebe (Greek mythology), the largest, which was discovered long before the others.

The discovery of 17 new moons in this group was announced in October 2019. A team led by Scott S. Sheppard using the Subaru Telescope at Mauna Kea discovered 20 new moons, each about 5 kilometres (3.1 mi) in diameter. 17 of these are thought to fit into the Norse group. One of these is the most distant moon of Saturn. A public naming contest for these moons will be restricted to names from Norse mythology.

The members of the group are (in order of increasing distance from Saturn):

• Phoebe
• Skathi (Skathi subgroup)
• S/2004 S 37
• S/2007 S 2
• Skoll (Skathi subgroup)
• Hyrrokkin (Skathi subgroup)
• Greip
• Mundilfari
• S/2004 S 13 (?)
• S/2006 S 1 (Skathi subgroup)
• S/2007 S 3 (?)
• Suttungr
• Saturn LIV
• Jarnsaxa
• Narvi (Narvi subgroup)
• Bergelmir (Skathi subgroup)
• Hati
• S/2004 S 17 (?)
• S/2004 S 12 (?)
• Saturn LIX
• Farbauti (Skathi subgroup)
• Thrymr
• Bestla (Narvi subgroup)
• S/2004 S 7 (?)
• Aegir
• Saturn LXI (Skathi subgroup)
• Saturn LV
• Saturn LVII
• Saturn LXII (Skathi subgroup)
• Saturn LVI
• S/2006 S 3 (Skathi subgroup)
• Saturn LXV
• Kari (Skathi subgroup)
• S/2004 S 28
• Loge
• Saturn LXVI (Skathi subgroup)
• Fenrir
• Ymir
• Surtur
• Saturn LXIII
• S/2004 S 21 (Skathi subgroup)
• S/2004 S 39
• S/2004 S 36 (Narvi subgroup)
• Fornjot
• Saturn LXIV
• Saturn LVIII

See also

• Stats of planets in the Solar System
• List of natural satellites

External links

• S. Sheppard's classification of Saturn's irregular moons