Erriapus
Erriapus /ɛriˈæpəs/, or Saturn XXVIII (28), is a prograde irregular satellite of Saturn. It was discovered by Brett Gladman, John J. Kavelaars and colleagues in 2000, and given the temporary designation S/2000 S 10. It was named Erriapo in August 2003 after Erriapus (also rendered Erriappus), a giant in Gaulish mythology; the name was changed from dative Erriapo to nominative Erriapus per IAU conventions in late 2007.
Discovery images of Erriapus taken by the CFHT in September 2000 | |
| Discovery | |
|---|---|
| Discovered by | John J. Kavelaars et al. |
| Discovery date | 2000 |
| Designations | |
Designation | Saturn XXVIII |
| Pronunciation | /ɛriˈæpəs/ |
Named after | Erriap(p)us |
Alternative names | S/2000 S 10 |
| Orbital characteristics | |
| Epoch 2000 January 1.5 | |
Semi-major axis | 17 507 200 km |
| Eccentricity | 0.462 |
Orbital period (sidereal) | 871.1 d (2.38 yr) |
| Inclination | 38.7 |
| Satellite of | Saturn |
| Group | Gallic group |
| Physical characteristics | |
| Dimensions | 16.30 × 10 × 6.34 km (modeled) |
Mean diameter | 10+50% −30% km |
Synodic rotation period | 28.15±0.25 h |
| Albedo | 0.06 (assumed) |
Spectral type | light red B−V=0.83, R−V=0.49 |
| 23.0 | |
| 13.7 | |
Erriapus is about 10 kilometres in diameter, and orbits Saturn at an average distance of 17.5 Gm in 871 days.
As a member of the Gallic group of irregular satellites, which share similar orbital characteristics and a light-red colour, Erriapus is hypothesized to have its origin in the break-up of a common progenitor of the group, or to be a fragment of its largest member, Albiorix. It has a rotation period of 28.15±0.25 h, and is thought to rotate on its side, giving it similar seasons to those of Uranus. With a fairly elongated shape, it is a candidate for a contact binary or binary moon.