Sycorax (moon)
Template:Short description {{#invoke:other uses|otheruses}} Template:Infobox planet Sycorax Template:IPAc-en is the largest irregular satellite of Uranus. It was discovered on 6 September 1997 on the Hale Telescope in California. Sycorax's orbit is retrograde, irregular, and much more distant than that of Oberon, the furthest of Uranus's regular moons. With a diameter of over Template:Convert, it is the largest irregular moon of Uranus. It has been hypothesized that Sycorax is a captured object, as opposed to one that formed with Uranus.
Discovery
Sycorax was discovered by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J. Kavelaars using the 200-inch Hale Telescope, together with Caliban. At the time, it was given the temporary designation S/1997 U 2.Template:Sfn Officially confirmed as Uranus XVII, it was named after Sycorax, Caliban's mother in William Shakespeare's play The Tempest. This follows the trend that all Uranian moons are named after Shakespearean characters or those from Alexander Pope's The Rape of the Lock.<ref name="USGS"/>
Orbit
Template:Legend2Template:·Template:Legend2Template:·Template:Legend2Template:·Template:Legend2Template:·Template:Legend2Template:·Template:Legend2
Sycorax follows a distant orbit, more than 20 times further from Uranus than the furthest regular moon, Oberon.Template:Sfn Its orbit is retrograde, moderately inclined and eccentric. The orbital parameters suggest that it may belong, together with Setebos and Prospero, to the same dynamic cluster, suggesting a common origin.Template:Sfn
The diagram illustrates the orbital parameters of the retrograde irregular satellites of Uranus (in polar co-ordinates) with the eccentricity of the orbits represented by the segments extending from the pericentre to the apocentre.
Physical characteristics
The diameter of Sycorax is estimated at Template:Convert, based on the thermal emission data from Spitzer and Herschel Space telescopes<ref name="TNOsCool9"/> making it the largest irregular satellite of Uranus, comparable in size with Puck and with Himalia, the biggest irregular satellite of Jupiter.
The satellite appears light-red in the visible spectrum (colour indices Template:Nowrap Template:Nowrap,Template:Sfn Template:Nowrap Template:Nowrap,Template:Sfn Template:Nowrap Template:Nowrap<ref name="Maris 2007" />), redder than Himalia but still less red than most Kuiper belt objects. However, in the near infrared, the spectrum turns blue between 0.8 and 1.25 μmTemplate:Clarify and finally becomes neutral at the longer wavelengths.<ref name="Romon 2001" />
The rotation period of Sycorax is estimated at 6.9 hours.<ref name="FarkasTakacs2017"/> Rotation causes periodical variations of the visible magnitude with the amplitude of 0.12.<ref name="FarkasTakacs2017"/> The rotation axis of Sycorax is unknown, though measurements of its light curve suggest it is being viewed at a near equator-on configuration. In this case, Sycorax may have a north pole right ascension around 356° and a north pole declination around 45°.<ref name="FarkasTakacs2017"/>
Origin
It is hypothesized that Sycorax is a captured object; it did not form in the accretion disk which existed around Uranus just after its formation. No exact capture mechanism is known, but capturing a moon requires the dissipation of energy. Possible capture processes include gas drag in the protoplanetary disk and many-body interactions and capture during the fast growth of Uranus's mass (so-called pull-down).Template:Sfn<ref name="Maris 2007" />
See also
References
Bibliography
External links
- Sycorax Profile (by NASA's Solar System Exploration)
- David Jewitt pages
- Uranus' Known Satellites (by Scott S. Sheppard)
- MPC: Natural Satellites Ephemeris Service
Template:Moons of Uranus Template:Uranus Template:Solar System moons (compact)