On the Scenario of the Moon Formation

Рассматривается задача гравитационного захвата околосолнечной Луны как возможный вариант образования спутника Земли. В модели трех тел (Солнце, Земля, Луна) производится отбор кривых сближений Луны и Земли, допускающих пересечение сферы Хилла Земли. Такие варианты повторяются в модели N-тел для оценки влияния приливных сил на перекачку орбитального момента Луны (P M orb) относительно Земли в ее собственный (P M s ∼ 10−6P M orb), что не приводит к захвату в короткой шкале времени ∼ 100 лет. Как показывает моделирование, захват Луны за одно сближение реализуется при учете небольшого (≈ 0.05 % от орбитальной скорости Луны) ее «притормаживания» за счет, например, столкновения с астероидом.The problem of gravitational capture of the Moon as near-sun planet is considered as a possible variant of the formation of the Earth satellite. In the model of three bodies (Sun, Earth, Moon), the Moon and Earth approaching trajectories are selected, allowing the intersection of the Earth’s Hill sphere. Such variants are repeated in the N-body model to assess the effect of tidal forces on the transfer of the orbital moment of the Moon (P M orb) relative to the Earth into its own (P M s ∼ 10−6P M orb), which does not lead to capture in a short timescale ∼ 100 years. It was shown that the capture of the Moon in one approach is realized if one takes into account a small (≈ 0.05 % of the orbital velocity of the Moon) “braking” due, for example, to a collision with an asteroid

Interstellar Planets and Comets: Origin Mechanisms, Discovery Ways, and Statistics

We consider mechanisms of origin and detection of interstellar planets and comets.Рассмотрены механизмы образования и обнаружения межзвездных планет и комет

Extremely Wide “Binary Stars”

В кратком обзоре ставится проблема эволюционной связи центральных околоядерных S-звезд и сверхскоростных звезд (СЗ), которые в недалеком прошлом были компонентами общей родительской двойной звезды, до ее захвата в галактический центр, населенный сверхмассивной черной дырой (СМЧД). Представляет интерес взаимной «реконструкции» популяций S-звезд и СЗ, рассчитанных в рамках классического сценария Хиллза, по принципу дополнения их наблюдательных данных. Обсуждается возможность «восстановления» из наблюдений S-СЗ-пар в Галактике.In a brief review, the problem of the evolutionary relationship between central near-nuclear S-stars and hypervelocity stars (HVS), which in the recent past were components of a parent binary star, before its capture into the galactic center inhabited by a supermassive black hole (SMBH), is posed. Of interest is the mutual ”reconstruction” of populations of S stars and HVS calculated within the framework of the classic Hills scenario, based on the principle of supplementing their observational data. The possibility of ”recovery” from observations of S-HVS-pairs in the Galaxy is discussed

Survival Probability for a Hypervelocity Star in Close Neighborhood of a Supermassive Black Hole

We present the results of numerical simulation on the probability of formation of a Hypervelocity Star (HVS) in the scenario of dynamic capture of a close binary system by the central black hole in the Galaxy and on the probability of its survival in the strong tidal field in the vicinity of the black hole. The results have been obtained for a series of pericentric distances. We applied a two-level numerical simulation implemented at first in the framework of the three-body problem used for evaluation of the HVS ejection velocity and then as an N-body approach that allowed us to establish the final status of the star: the degree of its destruction and mass loss. Probability estimations are based on a statistical ensemble of 10 000 initial configurations of the close binary with respect to the orbital phase of the components as well as to the inclination of the binary orbit to the plane of the orbit around the super-massive black hole and on the ensemble of 50 configurations for the three-body and N-body approaches, respectively

STATISTICAL RESEARCH IN EVOLUTIONARY GENETIC RELATIONSHIP OF DMS-, DW-, KW- AND KE-TYPES OF DOUBLE STARS

Statistical relations as spectrum-period, mass of primary component-semi-major axes of an orbit, excesses of luminosity and radius-mass of component, Karetnikov's diagram, modern and initial distributions of the binaries in the 1 ps3 of Sun neighbourhood allow to solve the problem of evolutionary relationship for close binary systems and describe conditions at which evolutionary transitions such as DMS -> DW -> KW <- KE take place

Ejection of Stars with Relativistic Velocities

We present the results of numerical simulations performed in terms of modified Hills' scenario involving two supermassive black holes (SMBHs). In contrast to the classic Hills scenario (Hills 1988), here one component of the ordinary stellar binary system is replaced with a SMBH that provides a kinetic resource for ejecting a star (the secondary component of the binary) with relativistic velocity (RVS). We examine the conditions that favor relativistic ejections of stars, depending on the pericentric approach, the mass ratio of two SMBHs, and the orbital configuration of the binary system. Applying the simple criteria helped us to sort out the results of numerical simulations by the outcome: conservation of the orbital configuration of the binary system, dynamic recapture of the star by the central SMBH, emission of hypervelocity stars (HVSs), and RVS ejection. In the framework of N-body simulations we estimate the probability for a star to survive in the cross-field of two SMBHs during the ejection with relativistic velocity, and discuss the probability of the detection of RVSs in our Galaxy in the cases where such stars are generated in distant interacting galaxies undergoing a merger of their central parts occupied by SMBHs

Tidal torque constants as a critical test for an evolution of close eclipsing binaries

Individual tidal torque λ 2,E 2 and apsidal-motion k 2 constants were calculated for 112 close eclipsing binaries (CEBs) with Detached components belonging to the Main Sequence (DMS-type) from the catalogue by Svechnikov and Perevozkina (Catalogue of orbital elements, masses and luminosities of variable stars of DMS-type and some results of its statistical treatment, Ural State University Press, Yekaterinburg, pp. 1-5, 1999) and for 95 detached binaries taken from the catalogue by Torres et al. (Astron. Astrophys. Rev. 18:67, 2010) on the base of theoretical evolutionary stellar models including tidal torque constants by Claret (Astron. Astrophys. 424:919, 2004). A method of the inversion of model track grid into isochrones was formulated as a complex interpolation procedure for DMS-binaries data. Sets of isochrones were computed in k 2-M, k 2-R, λ 2-M, λ 2-R, E 2-M, and E 2-R planes. Calculated tidal torque constants allow to test stellar structure theory by comparing observed and estimated values of apsidal motion period and analyzing the correlation between timescales of synchronization, circularization, magnetic braking, as well as nuclear burning of DMS-components. © 2011 Springer Science+Business Media B.V