arXiv subjects

Alexander E. Ershov

Publications and source records attributed to Alexander E. Ershov.

3 recordsLinked to original sources

arXiv2020

Effect of the surface shape of a large space body on its fragmentation in a planetary atmosphere

Employing the finite element and computational fluid dynamics methods, we have determined the conditions for the fragmentation of space bodies or preservation of their integrity when they penetrate into the Earth's atmosphere. The origin of forces contributing to the fragmentation of space iron bodies during the passage through the dense layers of the planetary atmosphere has been studied. It was shown that the irregular shape of the surface can produce transverse aerodynamic forces capable of causing deformation stress in the body exceeding the tensile strength threshold of iron.

astro-ph.EP↗

arXiv2020

On the possibility of through passage of asteroid bodies across the Earth's atmosphere

We have studied the conditions of through passage of asteroids with diameters 200, 100 and 50 m, consisting of three types of materials -- iron, stone and water ice across the Earth's atmosphere with the minimum trajectory altitude 10--15 km. The conditions of this passage with subsequent exit into outer space with the preservation of a substantial fraction of the initial mass have been found. The results obtained support our idea explaining one of the long-standing problems of astronomy -- the Tunguska phenomenon which has not received reasonable and comprehensive interpretations to date. We argue that Tunguska event was caused by an iron asteroid body, which passed through the Earth's atmosphere and continued to the near-solar orbit.

astro-ph.EP↗

arXiv2020

Hybrid modes in Al nanoparticles arrays

The mechanisms of coupling between the lattice modes of a two-dimensional (2D) array consisting of Al nanoparticles and the localized modes of individual Al nanoparticles have been studied in detail. The results have been obtained employing the finite-difference time-domain method (FDTD) and the generalized Mie theory. It was shown that interactions of single particles with 2D lattice modes significantly change the extinction spectra depending on the particle radius and the lattice period. The Rayleigh anomalies of higher orders contribute to formation of hybrid modes resulting in increase of the extinction efficiency in short wavelength range of the spectrum. It is shown that high intensity magnetic modes are excited in aluminum nanoparticles arrays. The patterns of spatial electromagnetic field distribution at the frequencies of hybrid modes have been studied. We note that comprehensive understanding the mode coupling mechanisms in arrays paves the way for engineering different types of modern photonic devices with controllable optical properties.

physics.optics↗