Ymir /ˈiːmɪər/, or Saturn XIX, is the second-largest retrograde irregular moon of Saturn. It was discovered by Brett J. Gladman, et al. in 2000, and given the temporary designation S/2000 S 1. It was named in August 2003 after Ymir, who in Norse mythology is the ancestor of all the Jotuns or frost giants.[12]
.jpg) Discovery image of Ymir taken by the La Silla Observatory in August 2000 | |
| Discovery[1] | |
|---|---|
| Discovered by | Brett J. Gladman |
| Discovery site | Observatoire de la Cote d'Azur |
| Discovery date | 2000 |
| Designations | |
Designation | Saturn XIX |
| Pronunciation | /ˈiːmɪər/,[2] /ˈɪmɪər/[3] |
Named after | Ymir |
| S/2000 S 1 | |
| Adjectives | Ymirian /ɪˈmɪəriən/[a][5] |
| Orbital characteristics[6] | |
| Epoch 2000 January 1.5 | |
| 22957100 km | |
| Eccentricity | 0.337 |
| −3.6 yr (−1315.16 d) | |
| 344.3° | |
| Inclination | 173.1° |
| 61.5° | |
| 90.8° | |
| Satellite of | Saturn |
| Group | Norse group |
| Physical characteristics[7][8][9] | |
| Dimensions | 24 km × 22 km × 16 km |
| 19+50% −30% km | |
| Circumference | 65 km (equatorial) |
| −11.92220±0.00002 h | |
North pole right ascension | 280°±20°[b] |
North pole declination | 70°±10°[b] |
| Albedo | 0.06[10] |
Spectral type | D/P |
| 21.7[11] | |
| 12.3 | |
It takes 3.6 Earth years to complete an orbit around Saturn. Of the moons that take more than 3 Earth years to orbit Saturn, Ymir is the largest, at about 19 kilometres (12 miles) in diameter;[11] Ymir is also the second largest member of the Norse group, after Phoebe.[9]
Spectral measurements from Cassini–Huygens show that Ymir is reddish in color, unlike Phoebe's gray color, suggesting a separate origin for this moon. It shows a similar light curve as Siarnaq and has a triangular shape, rotating in a retrograde direction about once every 11.9 hours.[9]
Notes
edit- ^ Because the -r is an inflectional ending, and the oblique stem is Ymi (as in Modern Norse Yme), one might expect the English adjective to be ?Ymian, but that is perhaps too short a word to be easily intelligible.[4]
- ^ a b Assuming the north pole is the one pointing north of the invariable plane, in accordance with IAU standards.
References
edit- ^ Brian G. Marsden (2000-10-25). "IAUC 7512". IAU. Retrieved 2011-01-08.
- ^ "Ymir". Merriam-Webster.com Dictionary. Merriam-Webster.
- ^ Merriam-Webster's Encyclopedia of Literature. 1995.
- ^ Budd (1898). "Norse Mythology". St. Mary's Hall lectures: and other papers. p. 84.
- ^ James Hall III (2015). Moons of the Solar System. p. 107.
- ^ Jacobson, R. A. (2007-06-28). "Planetary Satellite Mean Orbital Parameters". JPL/NASA. Retrieved 2008-02-14.
- ^ "Ymir (S/2000 S 1) – Tilmann Denk".
- ^ 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 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.
- ^ Nicholson, P. D. (2001),
{{citation}}: Missing or empty|title=(help) - ^ a b Sheppard, Scott S. "Saturn's Known Satellites". Department of Terrestrial Magnetism. Retrieved 2008-02-14.
- ^ Daniel W. E. Green (2003-08-08). "IAUC 8177: Sats OF (22); Sats OF JUPITER, SATURN, URANUS". IAU. Retrieved 2011-01-08.
External links
edit
- MPEC 2000-Y15: S/2000 S 1, S/2000 S 2, S/2000 S 7, S/2000 S 8, S/2000 S 9 (2000 Dec. 19 ephemeris)
- Ephemeris IAU-NSES
- Saturn's Known Satellites (by Scott S. Sheppard)
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