A stability study of Pluto's moon system

Abstract

The dynamical structure of the orbital element space of the Pluto–Charon system is studied in the model of the spatial circular restricted three‐body problem by using numerical methods. With the two newly discovered small satellites S/2005 P1 and S/2005 P2, the Pluto–Charon system can be considered as the first known binary system in which celestial bodies move in P‐type orbits. It is shown that the two satellites are in the stable region of the orbital element space and their origin by capture is unlikely. Also the large mass parameter allows the satellites to be regarded as a model of a new class of exoplanets orbiting around stellar binary systems.

An exploration of Pluto’s environment through stellar occultations

“…Moreover, most of the regions that we probed are dynamically unstable, due to the gravitational effects of the satellites, see Fig. 3 and Nagy et al (2006);Pires Dos Santos et al (2011). Thus, our lack of detection of sub-km moonlets is most probably the consequence of the larger satellites perturbations that ejected the smaller bodies, rather than the effect of a peculiar shallow cumulative size distribution with index q = 2.1.…”

“…Our results are Tholen et al (2008) for Charon, Nix and Hydra, and from Showalter et al (2011Showalter et al ( , 2012 for P4 and P5, and are indicated by the vertical dotted lines. The radii R unst,S (in Plutocentric distance, dashed line) is the boundary inside which stable S-orbits can exist around Pluto (Nagy et al 2006). Grey zones are regions of stability allowed by Nix and Hydra (Pires Dos Santos et al 2011). summarized in Fig.…”

“…Dynamical studies showed that stable additional satellites may exist around Pluto at specific regions of the phase space (Nagy et al 2006;Giuliatti Winter et al 2010;Pires Dos Santos et al 2011;Giuliatti Winter et al 2013), in particular between Nix and Hydra's orbits, as confirmed by the detection of P4, and inside Nix' orbit as confirmed by the detection of P5. It has also been suggested that collisions between Pluto's small satellites may have led to the formation of debris rings around the planet (Durda & Stern 2000;Steffl et al 2006).…”

“…5. Nagy et al (2006) studied the stability of putative rings on S orbits, i.e around Pluto alone, and on P orbits, i.e. around the barycenter of the Pluto-Charon system.…”

“…Moreover, search for rings in HST images by Steffl & Stern (2007) did not reveal material with I/F (standard measurement of reflectance for planetary rings, with I the observed intensity and πF, the incident solar flux) larger than ∼5 × 10 −7 (3σ limit) at more than 42 000 km from the Pluto-Charon barycenter, i.e. outside the minimum distance where dynamically stable rings are expected, see Nagy et al (2006) and details below. Here we report results obtained with a different method, which is based on the use of high signal-to-noise stellar appulses or occultations from the ground.…”