Origin of the Moon and Lunar Water

Three principal concepts regarding lunar formation have been examined: the accretion hypothesis, the mega-impact theory, and the multi-impact model. The multi-impact model amalgamates the salient facets of the mega-impact theory and the accretion hypothesis. As per this model, fragments of the terrestrial crust are ejected into space during collisions with numerous planetesimals (proto-asteroids) with diameters around 10-100 kilometers. This ejecta interacts with the accretion disk, augmenting its mass. Different models of lunar formation yield varied conclusions regarding the quantity of lunar water, its subsurface distribution, and isotopic composition. Geomorphological structures in the lunar polar regions (smoothed craters, landslides, regular patterns) suggest the presence of a substantial permafrost layer with an approximate thickness of a kilometer.Comment: Review article, published in "Earth and Planetary Science", 2023, 2(2

The NGST and the zodiacal light in the Solar system

We develop a physical model of the zodiacal cloud incorporating the real dust sources of asteroidal, cometary, and kuiperoidal origin. Using the inferred distribution of the zodiacal dust, we compute its thermal emission and scattering at several wavelengths (1.25, 5, and 20 $\mu$m) as a function of NGST location assumed to be at 1 AU or 3 AU. Areas on the sky with a minimum of zodiacal light are determined.Comment: 6 pages, incl. 2 colored figures, uses paspconf.sty. To be published in "The NGST Science and Technology Exposition" (eds. Eric P. Smith and Knox Long). Publications of the Astronomical Society of the Pacific, 200

Signatures of exosolar planets in dust debris disks

We apply our recently elaborated, powerful numerical approach to the high-resolution modeling of the structure and emission of circumstellar dust disks, incorporating all relevant physical processes. Specifically, we examine the resonant structure of a dusty disk induced by the presence of one planet. It is shown that the planet, via resonances and gravitational scattering, produces (1) an asymmetric resonant dust belt with one or more clumps intermittent with one or a few off-center cavities; and (2) a central cavity void of dust. These features can serve as indicators of a planet embedded in the circumstellar dust disk and, moreover, can be used to determine its major orbital parameters and even the mass of the planet. The results of our study reveal a remarkable similarity with various types of highly asymmetric circumstellar disks observed with the James Clerk Maxwell Telescope around Epsilon Eridani and Vega. The proposed interpretation of the clumps in those disks as being resonant patterns is testable -- it predicts the asymmetric design around the star to revolve, viz., by 1.2--1.6 deg/yr about Vega and 0.6--0.8 deg/yr about Epsilon Eri.Comment: to be published in ApJ Letters (v. 537, July 10, 2000), 5 pages, incl. 2 figures. Position of (color) Fig. 2 corrected to make the Figure caption fully readabl

The origin and rotation of binary asteroids

Binary asteroids were detected in a variety of dynamical populations, including Near-Earth Asteroids (NEAs), the main belt (MB), Trojans, and transneptunian objects (TNO). We discuss a new “multi-impact” model for origin of all classes of binary objects, including binary asteroids, Pluto–Charon, and the Earth–Moon systems. Basic elements of the model is the effective accumulation of multi-impact meteoritic ejecta in satellite orbits due to the collisional interaction between impact debris and initial low-massive ring around the primary body. The origin of satellites of all small planets in the Solar System is a result of numerous meteoritic impacts on a rotated small planet and accumulation of meteoritic ejecta around the primary body. An important prediction from the new model is that asteroids with satellites rotate faster than single asteroids. The model is confirmed by comparisons of spin rates of binary asteroids and single objects. Average spin rate for main-belt asteroid is 2.45 ± 0.05 rev/d (single objects) and 4.51 ± 0.21 rev/d (13 binary objects); direction of rotation of satellites is prograde only (three samples). Average spin rate for NEAs is 2.72 ± 0.26 rev/d (single objects) and 9.28 ± 0.25 rev/d (19 binary objects)