Mass and density of asteroids (4) Vesta and (11) Parthenope

Abstract

Abstract. As mentioned in a previous paper (Viateau & Rapaport 1997), the orbit of asteroid (17) Thetis is strongly perturbed by two large minor planets, (4) Vesta and (11) Parthenope. These strong gravitational perturbations enabled us to determine both the mass of Vesta and the mass of Parthenope. We also independently derived the mass of Vesta from observations of (197) Arete. The weighted mean of the two results gives the value (1.306 ± 0.016) 10 −10 M (solar mass) for the mass of Vesta, and its derived mean density is (3.3 ± 0.5) g/cm 3 . For (11) Parthenope, the values (2.56 ± 0.07) 10 −12 M and (2.3 ± 0.2) g/cm 3 were obtained, respectively for its mass and its mean density.

The Mass of (4) Vesta Derived From Its Largest Gravitational Effects

“…This suggests that our result is robust. Note that our result is very close to the 1.306 × 10 −10 M obtained by Viateau & Rapaport (2001). However, these two results were obtained assuming different masses of (11) Parthenope and by using different sets of observations.…”

“…Because of (11) Parthenope's large size, a diameter of about 162 km (Tedesco et al 2002), this asteroid induces large perturbations on the motion of (17) Thetis. Viateau & Rapaport (2001) determined the mass of (4) Vesta (the obtained value is (1.314 ± 0.018) × 10 −10 M ) from perturbing influences in the coordinates of (17) Thetis. For the mass determination of (11) Parthenope, they used astrometrical observations of (17) Thetis and (197) Arete.…”

Iron and Stony-Iron Meteorites

“…Finally . recent ground-based measurements of bulk densities for M asteroids 16 Psyche (Viateau, 2000;Britt ef aI., 2002) and 22 Kalliope (Margot and Brown, 2001) are ~2 g cm-3 , far below that expected for even highly fragmented core material. Equally puzzling is the lack of olivine-rich asteroids corresponding to the large numbers of asteroidal cores sampled by iron meteorites.…”

Smithsonian Institution

“…Without knowing the porosity of the surface, it is impossible to conclusively differentiate between these two types of assemblages. However, recent groundbased measurements of bulk densities, determined from astrometric observations, for M asteroids 16 Psyche (Viateau, 2000;Britt et al, 2002) and 22 Kalliope (Margot and Brown, 2001) are ~2 g/cm 3 . Their bulk densities are much lower than expected and may imply that these objects are not metallic in composition.…”