Photometry of Irregular Satellites of Uranus and Neptune

Abstract

We present BVR photometric colors of six Uranian and two Neptunian irregular satellites, collected using the Magellan Observatory (Las Campanas, Chile) and the Keck Observatory, (Manua Kea, Hawaii). The colors range from neutral to light red, and like the Jovian and the Saturnian irregulars (Grav et al. 2003) there is an apparent lack of the extremely red objects found among the Centaurs and Kuiper belt objects. The Uranian irregulars can be divided into three possible dynamical families, but the colors collected show that two of these dynamical families, the Caliban and Sycorax-clusters, have heterogeneous colors. Of the third possible family, the 168-degree cluster containing two objects with similar average inclinations but quite different average semi-major axis, only one object (U XXI Trinculo) was observed. The heterogeneous colors and the large dispersion of the average orbital elements leads us to doubt that they are collisional families. We favor single captures as a more likely scenario. The two neptunians observed (N II Nereid and S/2002 N1) both have very similar neutral, sun-like colors. Together with the high collisional probability between these two objects over the age of the solar system (Nesvorny et al. 2003, Holman et al. 2004), this suggests that S/2002 N1 be a fragment of Nereid, broken loose during a collision or cratering event with an undetermined impactor.

arXiv comment13 pages (including 3 figures and 2 tables). Submitted to ApJ Letters

References in corpus (6)

• Formation of Kuiper Belt Binaries
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• Near-Infrared Photometry of Irregular Satellites of Jupiter and Saturn
• The Short Rotation Period of Nereid
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• Nereid Has Complex Large-Amplitude Photometric Variability (Due to Chaotic Rotation)

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• Colors and Shapes of the Irregular Planetary Satellites
• Properties of the irregular satellite system around Uranus inferred from K2, Herschel and Spitzer observations
• Light curves and colours of the faint Uranian irregular satellites Sycorax, Prospero, Stephano, Setebos and Trinculo
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