Abstract
Four small moons (Styx, Nix, Kerberos and Hydra) are at present known to orbit around the barycenter of Pluto and Charon, which are themselves considered a binary dwarf planet due to their relatively high mass ratio. The central, non-axisymmetric potential induces moon orbits inconvenient to be described by Keplerian osculating elements. Here, we report that observed orbital variations may not be the result of orbital eccentricities or observational uncertainties, but may be due to forced oscillations caused by the central binary. We show, using numerical integration and analytical considerations, that the differences reported on their orbital elements may well arise from this intrinsic behavior rather than limitations on our instruments.
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Acknowledgements
We thank an anonymous referee for a thorough and insightful review that has improved this paper. The numerical code used in this work was branched from an n-body code (https://github.com/pmocz/nbody-python) created by Philip Mocz, that was based on the second-order leapfrog integration method (see, e.g., Springel et al. 2021). KNG acknowledges funding from grant FK 81641 “Theoretical and Computational Astrophysics,” ELKE. The authors thank Apostolos Christou for insightful comments on this manuscript. Part of this paper was written on Mountain Aroania in Greece, within a short distance from the mythological dwelling of the deity Styx, and the Styx spring.
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FK 8161, Theoretical and Computational Astrophysics, University of Patras.
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Gakis, D., Gourgouliatos, K.N. Orbit determination of the moons of the Pluto–Charon system. Celest Mech Dyn Astr 134, 14 (2022). https://doi.org/10.1007/s10569-022-10071-x
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DOI: https://doi.org/10.1007/s10569-022-10071-x