Communications of the Byurakan Astrophysical Observatory (ComBAO)
Volume 66, Issue 1, Sep 2019
Classification of BZCAT objects having uncertain types 0.3 MB
H. V. Abrahamyan, A. M. Mickaelian, G. M. Paronyan, G. A. Mikayelyan, M. V. Gyulzadyan
Abstract. In this work we try to understand some optical properties of blazars having uncertain types (BZU) in BZCAT vs. 5 Catalogue. Cross-correlation with SDSS reveals 43 BZU out of 227 that have spectra in SDSS. We have carried out spectral reclassification for these 43 blazar candidates (BZU) for activity types. As a result, 37 (86%) objects out of 43 changed their previous type.
The role of dipolar magnetic field of AGN in the morphology and evolution of extragalactic radio sources 0.4 MB
R. R. Andreasyan
Abstract. We discuss a model of formation of extragalactic radio sources when the parent optical galaxy has a large-scale dipolar magnetic field. The study of dynamics of ejected from the central part of optical galaxy clouds of relativistic particles in dipolar magnetic field gives a possibility to explain main morphological features and physical properties of formed extragalactic radio sources. We bring some results of statistical analyses and correlations between physical parameters for a large sample of extragalactic radio sources.
Saw-type shock fronts in several HII regions of southern hemisphere 0.3 MB
A. L. Gyulbudaghian
Abstract. Radiation shock fronts at the heads of non adiabatic cooling jets are considered. Decay of these shock fronts leads to the origin of groups of HH objects, and of groups of bright condensations in the jets expelled from the nuclei of galaxies, e.g. from the nucleus of NGC5128. Several examples of saw-type radiation shock fronts, found in the Southern Hemisphere, are presented.
On the correlation between average velocities of galaxies and their average luminosities in the closest large clusters of galaxies 0.2 MB
H. A. Harutyunian, A. M. Grigoryan, A. Khasawneh
Abstract. The evolution of baryonic matter caused by the interaction with the dark energy carrier and its possible influence on the spectral characteristics of atoms are considered. Taking into account the earlier conclusion about the secular growth of mass of atomic nuclei and (perhaps) elementary particles due to interaction with the dark energy carrier, we reach a conclusion that in the course of evolution the spectral series of chemical elements should undergo blueshift. The longer is the evolution path, the higher is blueshift. We show here that galaxies of the two nearest clusters of galaxies exhibit a luminosity-redshift negative correlation which was expected in the frame of this deductive reasonings.
Observations and Study of Byurakan-IRAS Galaxies: Summary 0.2 MB
G. A. Mikayelyan, A. M. Mickaelian, H. V. Abrahamyan, G. M. Paronyan, M. V. Gyulzadyan
Abstract. The paper is a summary and general analysis of optical spectroscopic data on 257 Byurakan-IRAS Galaxies (BIG objects) obtained with the BAO 2.6-m, SAO 6-m, OHP 1.93-m telescopes and taken from SDSS spectroscopic database. 149 star-formation regions galaxies, 42 galaxies with active nuclei, and 28 galaxies with a composite spectrum were identified. The spectra of 21 galaxies show signs of emission, but without the possibility of more precise determination of their activity type, 13 galaxies appear to have star formation rates that do not exceed normal, and 3 are absorption galaxies.
Some New Results in the Group-theoretical Description of the Radiation Transfer 0.2 MB
Abstract. The paper presents some new results of investigation developing the approach aimed at applying the group theory methods to radiation transfer problems. It consists of two separate parts. In the first part we derive new properties of supersymmetry of fundamental supermatrices - representations of composition and translation groups. It is shown that these supermatrices, which determine the layers adding to the two opposite boundaries of inhomogeneous medium, are connected with each other by the procedure of parity transposition. It is also demonstrated that, by analogy with the common second order matrices, the considered supermatrices can be factorized yielding the product of triangular supermatrices. The second part generalizes and applies the concept of composition groups to the case of media with spherical symmetry.
Some observational manifestations of the periodic inhomogeneity of atmospheres 0.3 MB
Abstract. We consider frequency and directional features of the reflectance and transmittance of an inhomogeneous scattering and absorbing atmosphere with the scattering albedo periodically varying with depth. The dependence of global optical properties of such media on optical thickness is found. Two different kind of problems are considered dependent on that by monochromatic or continuum, mono-directional or diffuse radiation illuminate the medium. The numerical results show how the observed intensities and line-profiles respond to the medium inhomogeneity with an uniform increase in optical thickness. Astrophysical aspects of these features are discussed.
Distribution of Elements Inside Stars 0.5 MB
Abstract. The chemical composition measured in stellar atmospheres is not necessarily the same as in deeper layers (outside the core). Indeed, for a significant fraction of main-sequence G to B types stars the discrepancies between superficial and internal abundances go from a few percent (for the coldest of these stars) to huge factors (for hot chemically peculiar stars). This is due to atomic diffusion process, which may produces elements segregation at some stages of the stellar evolution.
Study of Variability of 2MASSJ10183905+0014078 Stellar Objects 0.3 MB
E. C. Romas
Abstract. This paper presents observational data for the star 2MASSJ10183905+0014078 (UCAC4 452-048383), in which so far no brightness variability has been detected. However, photometric observations made in 2015 allowed recording are activity with an amplitude of 0.8 m for this star. The star parameters, namely magnitude and color index (V0 = 7.59, (B - V)0 = 1.19) and, therefore, the position on the Hertzsprung-Russell diagram, luminosity (L☉ = 0.1), spectral class (K7), mass (M☉ = 0.6), the spectral characteristics in the optical (Ca, Fe, Na D, H_ lines, Mg H, and TiO bands) and X-ray ranges allow us to classify the star as UVCet type object. The ash profile can be attributed to type II, with a relatively slow increase and decrease in brightness.
TUIMP: The Universe In My Pocket. Free astronomy booklets in all languages 0.2 MB
Abstract. TUIMP (www.tuimp.org) is an international project to produce little astronomy booklets. These booklets, folded from just one sheet of paper, can be used in classrooms, at open public conferences, or during visits of observatories and planetariums. They are free to download from the internet, the only thing which is needed is a color printer (in absence of a printer, the booklets can also be directly consulted on line, even with just a mobile phone). The booklets are intended for children from nine years old and for anyone curious of astronomy. They are written in a simple language, amply illustrated, revised and translated by professional astronomers. So far, they are being published in six languages, others languages are to come. Everyone is invited to download the booklets and use them in their outreach activities.
Catalog of cometary nebulae and related objects 1.1 MB
E. S. Parsamian, V. M. Petrosyan
Abstract. The catalogue of cometary nebulae and related objects is compiled using the known up to the publication date lists.
PhD THESES RELATED ARTICLES
Integrable systems connected with black holes 0.1 MB
Abstract. We studied some important questions in general relativity and mathematical physics mainly related to the two most important solutions of the theory of relativity - gravitational waves and black holes. In particular, the work is related to astrophysical shock waves, gravitational waves, black holes, integrable systems associated with them as well as their quantum equivalents. We studied the effects of null shells on geodesic congruences and suggested a general covariant definition of the gravitational memory effect. Thus, we studied observable effects that astrophysical shock waves can have on test particles after cataclysmic astrophysical events. We studied the geodesics of massive particles in Near Horizon Extremal Myers-Perry (NHEMP) black hole geometries. This is the space-time in the vicinity of the horizon of higher dimensional rotating black holes. Thus, this work can have applications for studying accretions of black holes. The system is also important in mathematical physics as it describes integrable (in special cases superintegrable) system, where the constants of motion are fully studied. On the other hand, the quantum counterparts of this and other integrable systems are studied as well and a new technique is suggested for geometrization of these systems.
The Origin of Non-Thermal Emission from FSRQs 1.2 MB
Abstract. The observations of astrophysical sources in a large frequency range (from radio to very high energy gamma-ray bands) provide complete information on the non-thermal processes taking place in different objects. Here, the origin of broadband emission from the jets of at-spectrum radio quasars are discussed. For the current study the blazars detected above 100 GeV: PKS 1441+25, 3C 279, PKS 1222+216, PKS 1510-089, as well as CTA 102, which was in flaring state in optcal/UV, X-ray and high energy gamma-ray bands, are selected. The publicly available data of Fermi LAT, Swift UVOT/XRT, Nustar telescopes have been analyzed, which enables to identify the prominent flaring and quiescent states for those sources, as well as, study the spectral properties, constrain the size and location of the emitting region.
The multiwavelength emission spectra of those sources, in different states, are modeled, which is crucial for understanding the particle acceleration and emission processes in their jets. For this purpose, a new code that can derive the model free parameters which statistically better describe the observed data is used. It derives the best-fit parameters and their uncertainties through Markov Chain Monte Carlo sampling of the likelihood distributions. By means of the detailed theoretical modeling of acquired data, it was possible to derive or at least constrain some crucial parameters such as the magnetic field, jet energetic, electron energy density etc.