S/2004 S 5: A new co-orbital companion for Dione

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2005.06.009 Byline: C.D. Murray, N.J. Cooper, M.W. Evans, K. Beurle Keywords: Satellites; general; Satellites of Saturn; Orbits; Resonances Abstract: We describe the astrometry and dynamics of S/2004 S 5 (provisionally named Polydeuces), a new satellite of Saturn, discovered in images recorded using the Imaging Science Subsystem (ISS) of the Cassini spacecraft. A total of 119 observations are presented, 101 of which were obtained with Cassini's narrow-angle camera and 18 using the wide-angle camera. Orbit determinations, based on a uniformly precessing ellipse model clearly showed S/2004 S 5 to be a possible co-orbital of Dione. By fitting a numerical solution of the full equations of motion to the available observations, we show that S/2004 S 5 is executing tadpole motion around Dione's L.sub.5 Lagrangian point, with a libration amplitude varying between +21.16[+ or -]0.03[degrees] and -31.68[+ or -]0.06[degrees] over a period of 791.3[+ or -]0.1 days. Author Affiliation: Astronomy Unit, School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK Article History: Received 11 March 2005; Revised 11 June 2005