Sinope (moon)

Infobox Planet
name = Sinope
bgcolour = #ffc0c0
discovery = yes
discoverer = S. B. Nicholson
discovered = July 21, 1914
mean_orbit_radius = 23,540,000 kmcite journal |last=Jacobson |first=R. A. |authorlink=Robert A. Jacobson |title=The Orbits of the Outer Jovian Satellites |journal=Astronomical Journal |year=2000 |volume=120 |pages=2679–2686 |doi=10.1086/316817 |url= http://www.iop.org/EJ/article/1538-3881/120/5/2679/200233.html]
eccentricity = 0.25
periapsis = 18,237,600 km
apoapsis = 30,191,200 km
period = 724.1 d (1.95 a)
avg_speed = 2.252 km/s
inclination = 128.11° (to the ecliptic) 153.12° (to Jupiter's equator)
satellite_of = Jupiter
physical_characteristics = yes
mean_radius = ~19 km
area = ~4500 km²
volume = ~28,700 km³
mass = 7.5e|16 kg
density = 2.6 g/cm³ (assumed)
surface_grav = 0.014 m/s² (0.001 g)
escape_velocity = ~0.023 km/s
albedo = 0.04 (assumed)
single_temperature = ~124 K

Sinope (pron-en|sɨˈnoʊpi respell|sə|NOH|pee, [ [http://dictionary.reference.com/browse/Sinope] ] or as in Greek "Σινώπη)" is a retrograde irregular satellite of Jupiter discovered by Seth Barnes Nicholson at Lick Observatory in 1914,cite journal |last=Nicholson |first=S. B. |title=Discovery of the Ninth Satellite of Jupiter |url=http://adsabs.harvard.edu//full/seri/PASP./0026//0000197.000.html |journal=Publications of the Astronomical Society of the Pacific |volume=26 |year=1914 |pages=pp. 197–198 |doi=10.1086/122336 ] and is named after Sinope of Greek mythology.

Sinope did not receive its present name until 1975cite journal |last=Nicholson |first=S. B. |title=The Satellites of Jupiter |url=http://adsabs.harvard.edu//full/seri/PASP./0051//0000093.000.html |journal=Publications of the Astronomical Society of the Pacific |volume=51 |issue=300 |pages=pp. 85–94 |date=April 1939 |doi=10.1086/125010 (in which he declines to name the recently discovered satellites (pp. 93–94))] [ [http://www.cfa.harvard.edu/iauc/02800/02846.html IAUC 2846: "Satellites of Jupiter"] 1974 October 7 (naming the moon)] ; before then, it was simply known as nowrap|Jupiter IX. It was sometimes called "Hades"cite book| last=Payne-Gaposchkin|first=Cecilia|coauthors=Katherine Haramundanis|title=Introduction to Astronomy|year=1970|publisher=Prentice-Hall|location=Englewood Cliffs, N.J.|isbn=0-134-78107-4] between 1955 and 1975.

Sinope was the outermost known moon of Jupiter until the discovery of Megaclite in 2000. The most distant moon of Jupiter now known is nowrap|S/2003 J2.

Orbit

Sinope orbits Jupiter on a high eccentricity and high inclination retrograde orbit. The orbital elements are as of January 2000. They are continuously changing due to Solar and planetary perturbations. It is often believed to belong to the Pasiphaë group.Sheppard, S. S.; and Jewitt, D. C.; [http://www.ifa.hawaii.edu/~jewitt/papers/JSATS/SJ2003.pdf "An Abundant Population of Small Irregular Satellites Around Jupiter"] , Nature, Vol. 423 (May 2003), pp. 261-263 ] However, given its mean inclination and different colour, Sinope could be also an independent object, captured independently, unrelated to the collision and break-up at the origin of the group.Grav, T.; Holman, M. J.; Gladman, B. J.; and Aksnes, K.; [http://arxiv.org/abs/astro-ph/0301016 "Photometric Survey of the Irregular Satellites"] , Icarus, Vol. 166 (2003), pp. 33-45] The diagram illustrates Sinope's orbital elements in relation to other satellites of the group.

Sinope is also known to be in a secular resonance with Jupiter, similar to Pasiphae. However, Sinope can drop out of this resonance and has periods of both resonant and non resonant behaviour in time scales of 10⁷ years.cite journal |last=Nesvorný |first=D. |authorlink=David Nesvorný |coauthors=Beaugé, C.; and Dones, L. |title=Collisional Origin of Families of Irregular Satellites |journal=The Astronomical Journal |volume=127 |year=2004 |pages=pp. 1768–1783 |url=http://www.iop.org/EJ/article/1538-3881/127/3/1768/203442.html |doi=10.1086/382099 ]

Physical characteristics

Sinope has an estimated diameter of 38 km (assuming an albedo of 0.04) The satellite is red (colour indices B-V=0.84, R-V=0.46). unlike Pasiphae which is grey.

Its infrared spectrum is similar to D-type asteroids also different from Pasiphae.cite journal |last=Grav |first=T. |coauthors=and Holman, M. J. |title=Near-Infrared Photometry of the Irregular Satellites of Jupiter and Saturn |journal=The Astrophysical Journal |volume=605 |year=2004 |pages=pp. L141–L144 |url=http://arxiv.org/abs/astro-ph/0312571 |doi=10.1086/420881 ] These dissimilarities of the physical parameters suggest a different origin from the core members of the group.

See also

* Irregular satellite
* Sinope in fiction
* Ephemeris [http://www.cfa.harvard.edu/iau/NatSats/NaturalSatellites.html IAU-MPC NSES]

References

External links

* [http://solarsystem.nasa.gov/planets/profile.cfm?Object=Jup_Sinope Sinope Profile] by [http://solarsystem.nasa.gov NASA's Solar System Exploration]
* [http://www.ifa.hawaii.edu/~jewitt/irregulars.html David Jewitt pages]
* [http://www.ifa.hawaii.edu/~sheppard/satellites/urasatdata.html Scott Sheppard pages]