Photographic photometry for stellar statistics with Tautenburg Schmidt telescope

Photometric properties of deep Tautenburg Schmidt plates in the UBV system over the whole field and over a wide range of stellar magnitudes are discussed. Different reduction models based on the calibration curve alone and with additional terms containing colour and plate coordinates are considered. With the filter-emulsion combinations used the Johnson UBV system can be reproduced quite well by the Tautenburg telescope. The accuracy of photometric data can be improved if geometrical terms are taken into account. For deep plates with a significant effect of background nebulosity a supplementary term is to be included in the reduction model. The polynomial coefficients vary in dependence on spectral bands and individual properties of each plate.     

Quantum string theory in curved space-times

A general method to quantize strings in curved space-times is exposed. It treats the space-time metric exactly and the string excitations small as compared with the energy scale of the geometry. The method is applied to cosmological (de Sitter) and black-hole (Schwarzschild) geometries. The critical dimension decreases in one for de Sitter and stays unaltered for black-holes as compared with flat space-time values. Bogoliubov transformations in the context of string theory are derived and the Bogoliubov coefficients describing elastic and inelastic scattering and excitation of modes are computed explicitely. The string-black-hole cross section is derived and a pair mode creation phenomena is found. The quantization and scattering of strings in shockwave geometries (ultrarelativistic boosted black-holes or Aichelburg-Sexl space time) is found to be exactly solvable.     

On Limb Observations of Bolides

The LP/OMPS limb sensor of the Suomi satellite detected the atmospheric trace of the Chelyabinsk superbolide with an energy of over 400 kt TNT in 2013. The study of LP/OMPS data shows that it detects several bolides with much less energy each year. The paper considers the cases of observation of three bolides in 2016–2017: on February 6, 2016 (13 kt), March 3, 2016 (0.19 kt), and March 9, 2017 (1 kt). The possibility of improving the detection of bolides using a limb sensor in the form of a microsatellite with an increased number of observation regions along the horizon is discussed. Several such microsatellites will be able to track most of the bodies larger than a meter that burn up in the atmosphere of the Earth or Mars.

     

On the Question of Calculating the Parameters of Vortices in the Near-Surface Atmosphere of Mars

Solar System Research - The paper is dedicated to the study of dust vortices on the Earth and Mars. The hydrodynamic similarity of convective vortices is considered, and the similarity criteria are...     

Venera-D Mission Scenario and Trajectory

Solar System Research - The article describes the trajectory scenario for the Venera-D mission. The main aspects of optimal launch dates are considered. A scenario, which enables insertion of an...     

Formation of Hydrogen Emission Lines in the Magnetospheres of Young Stars

Astronomy Letters - The formation of hydrogen emission lines in the magnetospheres of young stars is considered. The magnetosphere is assumed to be formed by a dipolar magnetic field whose axis is...     

Detection of Methanol Maser Flares Near 19.9 and 20.9 GHz toward the Massive Source of Active Star Formation G358.931-0.030

Astronomy Letters - We have investigated the methanol CH3OH lines at frequencies of 19.967 GHz [21-30 E(vt = 0) transition] and 20.971 GHz [101-112 E+(vt = 1) transition] toward the massive region...     

Upgrading of Oil Shale by Flotation Without Collector

Natural Resources Research - Oil shale impurities prevent its direct usage as a source of energy. Removing or reducing of these impurities before retorting can reduce the cost of oil shale...     

Modeling the Seasonal Dynamics of the Diurnal Variation of the Global Electric Circuit

Izvestiya, Atmospheric and Oceanic Physics - On the basis of a parametrization of the ionospheric potential (IP), the seasonal dynamics of the diurnal IP variation for 2016–2017 is simulated...     

Self-Similarity Properties of the Kerch Peninsula Stream Network and Their Comparison with the Results of Structural and Geomorphological Analysis

Izvestiya, Atmospheric and Oceanic Physics - The results of the fractal analysis of a drainage network reconstructed using a digital elevation model and the structural and geomorphological analysis...