Determination of the masses of planetary satellites from their mutual gravitational perturbations

We analyze the possibility of determining the masses of outer planetary satellites from their mutual gravitational perturbations via ground-based observations. Such a technique has been applied in (Emelyanov, 2005b) to determine the mass of the Jovian satellite Himalia. In this paper, we use the least-squares method to compute the errors of satellite masses inferred from simulated observations. We analyze several of the most suitable variants of groups of outer satellites of planets with maximum mutual attraction. We found that the mass of the Satumian satellite Phoebe (S9) can be refined by continuing observations of the satellite S25 Mundilfari until 2027. We show that the masses of other known outer planetary satellites cannot be determined from ground-based observations.     

Resonant motion of trans-Neptunian objects in high-eccentricity orbits

A substantial fraction of the Edgeworth-Kuiper belt objects are presently known to move in resonance with Neptune (the principal commensurabilities are 1/2, 3/5, 2/3, and 3/4). We have found that many of the distant (with orbital semimajor axes a > 50 AU) trans-Neptunian objects (TNOs) also execute resonant motions. Our investigation is based on symplectic integrations of the equations of motion for all multiple-opposition TNOs with a > 50 AU with allowance made for the uncertainties in their initial orbits. Librations near such commensurabilities with Neptune as 4/9, 3/7, 5/12, 2/5, 3/8, 4/27, and others have been found. The largest number of distant TNOs move near the 2/5 resonance with Neptune: 12 objects librate with a probability higher than 0.75. The multiplicity of objects moving in 2/5 resonance and the longterm stability of their librations suggest that this group of resonant objects was formed at early formation stages of the Solar system. For most of the other resonant objects, the librations are temporary. We also show the importance of asymmetric resonances in the large changes in TNO perihelion distances.     

Geological structure of the submarine Vityaz Ridge within the <Emphasis Type="Italic">Seismic Gap</Emphasis> area (Pacific slope of the Kurile island arc)

Results of geological research conducted by the Pacific Oceanological Institute of the Far East Division of the Russian Academy of Sciences and the Institute of Oceanology of the Russian Academy of Sciences on the submarine Vityaz Ridge during Cruise 37 of R/V Akademik M.A. Lavrentyev in 2005 are discussed. Various rocks constituting the basement and sedimentary cover of the ridge were dredged in three areas of the ridge. Based on isotope geochronology, petrogeochemical, petrographic, and paleontological data and comparison with similar rocks available from the adjacent land and Sea of Okhotsk, they are subdivided into several age complexes. Late Cretaceous, Eocene, Late Oligocene, Miocene, and Pliocene-Pleistocene complexes are defined among the igneous rocks, while volcanogenic-sedimentary rocks are united into Late Cretaceous-Early Paleocene (late Campanian-Danian), undivided Paleogene (Paleocene-Eocene?), Oligocene-early Miocene, and Pliocene-Pleistocene complexes. The obtained data on the age and formation settings of the defined complexes made it possible to reconstruct the geological evolution of the central Pacific slope of the Kurile island arc.