Masses and densities of Pluto and Charon

Null, G. W.; Owen, W. M.; Synnott, S. P.

doi:10.1086/116610

Cited by 33 publications

(15 citation statements)

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“…Yet the resulting semi-major axis a ¼ 19525 AE 40 km is somewhat smaller than the currently adopted value of a ¼ 19636 AE 8 km (Tholen and Buie, 1997). Nevertheless our result is similar to those derived by several other authors (Null et al, 1993;Young et al, 1994). We remind that the value of the semi-major axis has some implications on the mutual-event based radii of Pluto and Charon.…”

Section: Analysis Of Each Astrometric Setsupporting

confidence: 85%

Orbit of an Astrometric Binary System

Descamps

2005

Celestial Mech Dyn Astr

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We present a new method to solve the problem of initial orbit determination of any binary system. This method is mainly based on the material available for an observer, for example relative positions at a given time of the couple in the ''plane of sky'', namely the tangent plane to the celestial sphere at the position of the primary component. The problem of orbit determination is solved by splitting in successive stages in order to decorrelate the parameters of each other as much as possible. On one hand, the geometric problem is solved using the first Kepler's law from a single observing run and, on the other hand, dynamical parameters are then inferred from the fit of the Kepler's equation. At last, the final stage consists in determining the main physical parameters involved in the secular evolution of the system, that is the spin axis and the J 2 parameter of the primary if we assume that it is a quasispherical body. As a matter of fact there is no need to make too restrictive initial assumptions (such as circular orbit or zero eccentricity) and initial guesses of parameters required by a nonlinear least-squares Levenberg-Marquardt algorithm are finally obtained after each stage. Such a protocol is very useful to study systems like binary asteroids for which all of the parameters should be considered a priori as unknowns. As an example of application, we used our method to estimate the set of the Pluto-Charon system parameters from observations collected in the literature since 1980.

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Section: Analysis Of Each Astrometric Setsupporting

confidence: 85%

Orbit of an Astrometric Binary System

Descamps

2005

Celestial Mech Dyn Astr

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“…In Table 1 a chronology of mass ratios and mass parameters μ= m C /( m P + m C ) is shown, where m P and m C are the masses of Pluto and Charon, respectively. Several authors have struggled to obtain this quantity from measurements of the barycentric wobble (Null, Owen & Synnott 1993; Young & Binzel 1994; Null & Owen 1996; Foust et al 1997; Tholen & Buie 1997; Olkin, Wasserman & Franz 2003). In addition the Pluto–Charon system is remarkable, since in the Solar system Charon is the largest moon relative to its primary, with the highest mass ratio of 0.1166 (Tholen et al 2008, hereafter T08).…”

Section: Introductionmentioning

confidence: 99%

Detailed survey of the phase space around Nix and Hydra

Süli

Zsigmond

2009

Monthly Notices of the Royal Astronomical Society

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We present a detailed survey of the dynamical structure of the phase space around the new moons of the Pluto - Charon system. The spatial elliptic restricted three-body problem was used as model and stability maps were created by chaos indicators. The orbital elements of the moons are in the stable domain both on the semimajor axis - eccentricity and - inclination spaces. The structures related to the 4:1 and 6:1 mean motion resonances are clearly visible on the maps. They do not contain the positions of the moons, confirming previous studies. We showed the possibility that Nix might be in the 4:1 resonance if its argument of pericenter or longitude of node falls in a certain range. The results strongly suggest that Hydra is not in the 6:1 resonance for arbitrary values of the argument of pericenter or longitude of node.Comment: Published in MNRAS. 10 pages, 7 figures, 4 table

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“…With greater attention to achieving the best possible seeing, some direct imaging observations now compete with HST. The bulk density of Charon has been measured both from HST and from the ground, showing that Charon has a lower density than Pluto (Null et al 1993, Young et al 1994, Null and Owen 1996. Even newer techniques based on adaptive optics on the largest telescopes are also being turned toward imaging, photometric, and spectroscopic investigations.…”

Section: Introductionmentioning

confidence: 99%