Search

Purpose: The results of research in continuum decameter-wave radio emission of the Galaxy background, ionized hydrogen regions, supernova remnants, extragalactic discrete sources, extended galaxies, galactic clusters, extragalactic background are given. The aim of this work is reviewing the results achieved for over 50-years of the UTR-2 radiotelescope research of our Galaxy and its population, as well as extragalactic radio sources in the continuum radio emission spectrum at extremely low frequencies for the ground based observations. Design/methodology/approach: The review, analysis, collection of archival data in various publications related to the subjectof this work. Findings: The basic results of studying the ionized hydrogen regions, supernova remnants, Galaxy background emission and its large-scale structure are given, and the maps of these sources are obtained. The catalog of extragalactic discrete radio sources of the most Northern sky part and the cosmological conclusions based on its analysis are described; the estimate of the isotropic extragalactic background brightness temperature is obtained; for the first time, the observational results for the Andromeda galaxy and two galactic clusters Coma and A2255 are given briefly. Conclusions: All the results presented here emphasize the uniqueness and importance of research in the decameter wavelength range, and the large area, flexibility of structure, continuous improvement make the UTR-2 radio telescope an indispensable tool for solving the most important tasks of modern radio astronomy, despite its respectable age. For example, only in the range of 10 to 30 MHz the ionized part of the most common element in the universe, the hydrogen, becomes optically thick and begins to absorb the synchrotron emission on the line of sight, which allows rather easy separation of thermal and non-thermal components of radioemission. This property allows to determine the ionized hydrogen regions’ electron temperature and the electron concentration on the line of sight independently in studying the hydrogen emission regions. When studying the supernova remnants, we can determine the ionized matter location by their spectrum drops ‒ before, inside or behind the remnant. Based on the HB3 supernova remnant radio imagies, an assumption was made on the existence of an ionized hydrogen relic shell aroundit, being caused by the initial ultraviolet flash of a supernova. For the first time, the maps of the Northern sky large-scale structure in the declination range from ‒15° to +85° at extremely low frequencies 10, 12.6, 14.7, 16.7, 20 and 25 MHz for the ground-based observations are published, which, besides their own scientific value, may allow to correct the UTR-2 radio telescope imaging results. Using the full-resolution UTR-2 maps and the developed method of multifrequency T‒T diagrams, it was possible to separate the background radiation into galactic and extragalactic components and construct the spectrum of the latter. From the analysis of the most complete decameter wavelength range catalog of discrete sources, it follows that there is a gap in the redshift spatial distribution for all classes of extragalactic sources. The existence of an ionized hydrogen ring in the Andromeda Nebula disk has been suggested. It is shown that the main partof the galaxy clusters decameter-wave emission comes from haloes and relics.

Purpose: Some peculiarities of emission of Class I methanol masers on the 80–71A+ transition at 95 GHz in sources closely associated with protostar-forming regions and in supernova remnants are studied. Here belongs the investigation of SiO (J=2–1) maser variability in R Cassiopeiaе, too. Design/methodology/approach: Search for Class I methanol masers is based on the idea of coincidence of regions of their emission with sources of OH masing transition in the bottom level of energy at frequency of 1720 MHz (2Π3/2 J=3/2 F=2–1). Findings: Two methanol masers on transition 80–71A+ (95 GHz) in the supernova remnants IC 443 and Kes 79 are detected. Variabilities of SiO maser emission on transition J=2–1 in R Cassiopeiaе are shown for the first time. Conclusions: Variability of methanol and SiO masers is their general feature. On the example of three objects, the possibility of using the 1720 MHz OH maser as an indicator in the search for Class I methanol masers is shown. Especially it is important in the study of methanol maser emission in supernova remnants that has been proved to be true by detection of methanol masers on transition 80–71A+ (95 GHz) in IC 443 and Kes 79. Features of spectra variability of emission in R Cassiopeiaе testify to formation and disappearance of SiO (J=2–1) masers.

Аn analytical solution for a spherically stratified medium is constructed on the strength of an earlier obtained exact solution of Kompaneets equation for the shock front in a planar stratified medium with the density changing as the hyperbolic tangent. The solution obtained allows to build entirely the shock front and explore its evolution for different values of independent parameters (density gradient, explosion point position, scale of inhomogeneity) which varying can permit simulation of real conditions while obtaining information on medium properties and supernova remnant evolution.