Greip /ˈɡreɪp/ or Saturn LI is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden on 26 June 2006, from observations taken between 5 January and 1 May 2006. Greip is about 5 kilometres in diameter, and orbits Saturn at an average distance of 18,066 Mm in 906.556 days, at an inclination of 172.7° to the ecliptic (159.2° to Saturn's equator), in a retrograde direction and with an eccentricity of 0.3735, and is presumably at high risk of eventually colliding with Phoebe.[3] It is unknown whether Greip is more similar to Suttungr or Hyrrokkin in color.[3] Its rotation period is most likely 12.75±0.35 hours with two minima in the light curve,[2] but a longer period of 19 hours cannot be ruled out due to the short observation time by Cassini–Huygens.[3]
 Greip imaged by the Cassini spacecraft in September 2015 | |
| Discovery | |
|---|---|
| Discovered by | Scott S. Sheppard David C. Jewitt Jan T. Kleyna Brian G. Marsden |
| Discovery date | 2006 |
| Designations | |
Designation | Saturn LI |
Named after | Greipa |
| S/2006 S 4 | |
| Orbital characteristics[1] | |
| 18206000 km | |
| Eccentricity | 0.326 |
| −921.2 days | |
| Inclination | 179.8° |
| Satellite of | Saturn |
| Group | Norse group |
| Physical characteristics[2][3] | |
Mean diameter | 5+50% −30% km |
| 12.75±0.35? h | |
| Albedo | 0.06 (assumed) |
| 24.4 | |
| 15.4 | |
It is named after Greip, a giantess in Norse mythology.
References edit
- ^ S.S. Sheppard (2019), Moons of Saturn, Carnegie Science, on line
- ^ a b Denk, T.; Mottola, S. (2019). Cassini Observations of Saturn's Irregular Moons (PDF). 50th Lunar and Planetary Science Conference. Lunar and Planetary Institute.
- ^ a b c d Denk, Tilmann; Mottola, Stefano; Tosi, Frederico; Bottke, William F.; Hamilton, Douglas P. (2018). "The Irregular Satellites of Saturn" (PDF). In Schenk, P.M.; Clark, R.N.; Howett, C.J.A.; Verbiscer, A.J.; Waite, J.H. (eds.). Enceladus and the Icy Moons of Saturn. Space Science Series. Vol. 322. Tucson, AZ: The University of Arizona Press. pp. 409–434. Bibcode:2018eims.book..409D. doi:10.2458/azu_uapress_9780816537075-ch020. ISBN 9780816537075.
External links edit
- Institute for Astronomy Saturn Satellite Data
- IAUC 8727: Satellites of Saturn June 30, 2006 (discovery)
- MPEC 2006-M45: Eight New Satellites of Saturn June 26, 2006 (discovery and ephemeris)
- IAUC 8873: Satellites of Saturn September 20, 2007 (naming)