Internal Gravity and Infrasound Waves during the Hurricane of May 29, 2017, in Moscow

Izvestiya, Atmospheric and Oceanic Physics - Data on internal gravity and infrasound waves recorded during the passage of both warm and cold fronts throughout Moscow, which are associated with the...     

The impact of large-scale turbulence on the redistribution of angular momentum in stellar accretion disks

We consider the origin and development of large-scale turbulence in a shear flow in a stellar accretion disk. The ratio of the kinetic energy of vortices originating in the turbulent flow and the total initial kinetic energy of the rotating disk is essentially constant. The large-scale structures that form are able to redistribute the angular momentum without any appreciable heating of the matter.     

The role of winter flaw polynyas in the formation of ice and hydrologic conditions in the Siberian shelf seas in the summer period

This paper analyzes the influence of flaw polynyas of the seas of the Siberian shelf on the formation of ice conditions in summer based on the ten-day data on the areas of flaw polynyas for 1978–2002 obtained by satellite image processing. The results of forecasts of summer ice conditions in the seas of the Siberian shelf are presented. The correspondence between the forecasts and observed data is 94.7% on average. The interrelation of atmospheric and ice processes is shown for the case when winter atmospheric processes determine ice conditions for the following summer and fall.     

Astrokit-an efficient program for high-precision differential CCD photometry and search for variable stars

Having a need to perform differential photometry for tens of thousands stars in a several square degrees field, we developed Astrokit program. The software corrects the star brightness variations caused by variations of atmospheric transparency: to this end, the program selects for each star an individual ensemble of reference stars having similar magnitudes and positions in the frame. With ten or more reference stars in the ensemble, the differences between their spectral types and the spectral type of the object studied become unimportant. A strokit searches for variable stars using Robust Median Statistics criterion, which allows candidate variables to be selected more efficiently than by analyzing the standard deviation of star magnitudes. The software allows very precise automatic analysis of long inhomogeneous sets of photometric observations of a large number of objects to be performed, making it possible to find “hot Jupiter” type exoplanet transits and low-amplitude variables. We describe the algorithm of the program and the results of its application to reduce the data of the photometric sky survey in Cygnus as well as observations of the open cluster NGC188 and the transit of the exoplanet WASP-11 b /HAT-P-10 b, performed with the MASTER-II-URAL telescope of the Kourovka Astronomical Observatory of the Ural Federal University.     

A new stage in the development of ablative pulsed plasma thrusters at the RIAME

This paper presents an overview of the works on ablative pulsed plasma thrusters (APPTs) carried out at the Research Institute of Applied Mechanics and Electrodynamics (RIAME). The main features of next generation thrusters developed at the RIAME in the 2000s are discussed together with the optimization criteria for APPTs intended for use in correction propulsion systems of small spacecraft, e.g., MKA-FKI (developed by the Lavochkin Association) and Soyuz-Sat-O (developed by Maksimov Space Systems Research Institute and the Production Corporation Polyot).     

Stratigraphy of the Maikop Group and Pteropoda Beds in northern Azerbaijan

Deepwater sections of the Maikop Group (Oligocene-lower Miocene) and overlying lower-middle Miocene sediments are studied near the Perekishkyul Settlement in lower reaches of the Sumgait River, northern Azerbaijan. Several lithological reference levels and the Spiratella (Pteropoda) Beds are used to correlate preliminarily these uniform clayey sections barren of benthic fossils. Based on distribution of the organicwalled and calcareous phytoplankton, spores, pollen and ichthyofossils, the sections are first subdivided in detail and dated. Distinguished in the sections are two regional levels characterizing distortions in the basin hydrological regime during the late Oligocene (level with large Leiosphaeridia and Pterospermella) and Burdigalian (level with dominant dinocysts of the genus Batiacasphaera), and separate intervals with diverse phytoplankton and ichthyofossils. The Tarkhanian sediments are marked by first-appearing oceanic nannoplankton with Sphenolithus heteromorphus and deepwater ichthyofauna with Vinciquerria merklini. The Karaganian is established at the first occurrence level of peculiar endemics (Sardinella karaganica W. Dan. and Mugil karaganicus Swich.) among ichthyofauna.