Communications of the Byurakan Astrophysical Observatory (ComBAO)
Volume 69, Issue 1, August 2022
Can the Existence of Dark Energy Shed Light on the Dark Sides of the "Byurakan Concept"? 0.2 MB
H. A. Harutyunian
Abstract. The Ambartsumian’s idea on the existence of superdense matter and its decay due to evolution is considered using the new observational data. We suggest a new approach to the problem using the number density of baryons for describing the cosmic object instead of mass density. The atomic nuclei and baryons increase their mass due to the gradual decrease of the nuclear binding energy, which, in its turn, takes place as a result of the influence of dark energy. This effect increases the mass of all cosmic objects and the Universe as a whole. Apparently, the smart mechanism of transformation of the mass into energy and vice versa in the atomic nuclei level regulates mass density everywhere. The self-consistent change of the baryonic mass and their number density maintain the balance in the baryonic world.
Fine classification of the emission-line spectra of active galaxies 0.6 MB
A. M. Mickaelian, H. V. Abrahamyan, G. A. Mikayelyan, G. M. Paronyan
Abstract. We refine the classification of galaxies by activity types based on a number of samples of objects having homogeneous optical medium resolution spectra from SDSS. SDSS spectra provide many spectral features and details that were not available before. Three diagnostic diagrams and eye examination have been used and the combined activity types have been derived. A fine classification scheme was developed, where QSOs have subtypes like Seyferts, Narrow Line QSOs are introduced, subclasses for Narrow Line Seyfert 1s are used and Composite spectrum objects have their subtypes. This classification scheme much better describes all fine details in the optical spectra and allows further study of active galaxies by the subtypes for better understanding the Unified model and the physical properties of AGN and Starbursts.
The Spectral Line Evolution in a Semi-infinite Atmosphere with Local Time-dependent Energy Sources 0.2 MB
Abstract. The time-dependent problem of spectral line formation in a one-dimensional semi-infinite scattering and absorbing atmosphere containing a local energy source radiating equally in both directions is considered. The energy release is assumed to be non-stationary and to be either δ(t)-shaped or of the unit jump form given by the Heaviside H(t) function. The main attention is paid to the temporal dependence of the observed line profiles on the depth of energy eruption in the atmosphere. The role of scattering in the continuous spectrum is emphasized.
Gasdynamical flows in star forming regions 0.3 MB
A. G. Yeghikyan
Abstract. A review of gas-dynamical flows in astrophysics is given with an emphasis on accretion flows and outflows. Analytical estimates of the dependence of the velocity and density on the radius during spherical accretion are considered, as well as the rate of mass inflow and the corresponding luminosity of the accretion disk are also estimated. Some features of gas inflow and outflow near the star are mentioned, like mass-loading flows where source functions of mass and momentum are presented and analyzed. The velocities and radii of the ionization fronts of hot stars are considered. The Sedov-Taylor analytical formula on the dependence of the radius of the fireball on time during a strong explosion is given, where the explosion energy and density of the medium act as parameters. Examples of the use of dimensional theory in astrophysics, in particular, in accretion flows used above are considered. An example of a numerical solution of the interaction of an interstellar cloud with the solar wind is also given, followed by an estimate of the inflow of the cloud’s gas environment into the Earth’s atmosphere, which affects the terrestrial ozone content.
Growth of accreting intermediate mass black hole seeds 0.3 MB
Abstract. This communication aims to review the mass assembly history of seed black holes to the present time of accreting intermediate mass black hole (IMBH)-candidates. Given the masses and redshifts at present time of 137 IMBH-candidates collected from the literature, we have undertaken a large series of numerical simulations to achieve this goal. The crux is that, we utilize the microscopic theory of black hole (MTBH), which explores the most important novel aspects expected from considerable change of properties of space-time continuum at spontaneous breaking of gravitation gauge symmetry far above nuclear density. As a corollary, this theory has smeared out the central singularities of BHs, and makes room for their growth and merging behavior. We compute among the others the masses, the growth-time scales, TBH , and the redshifts of seed BHs. In particular, for the present masses log(M/[M⊙]) = 2.20 to 5.99 of IMBH-candidates, the computed seed masses are ranging from log(M seed/[M⊙]) = −0.50 to 3.29, with corresponding growth-time scales TBH ranging from log(TBH /[yr]) = 8.82 to 10.09. We derived scaling mass-luminosity relation, by means of which we compute the luminosities of IMBH-candidates ranging from log(L/[erg s−1]) = 39.13 to 41.653.
Gaia EDR3 Data For Three Young Stellar Objects 0.2 MB
K. S. Gigoyan, N. M. Azatyan, K. K. Gigoyan
Abstract. We present Gaia Early Data Release 3 (Gaia EDR3) high accurate astrometric and photometric data and also Catalina Sky Survey (CSS) phase-dependent light curves for three Young Stellar Objects (YSO). They are LRL 245, 2MASS J04300424+3533238, and CVSO 592. These tree YSOs are presented as periodic variables in the Catalina Surveys Data Release-1 (CSDR1) data base CSS phase-dependent curve of LRL 245 shows periodicity with period P=234.66 days and amplitude ∆m≈4.0 mag. For this object high-resolution spectra in H-band (from 1.51 to 1.69 μm) was obtained by the APOGEE instrument. LAMOST telescope moderate-resolution CCD spectra is available for object 2MASS J04300424+3522238 only. The spectra shows clear features of M dwarfs.
Properties of interstellar matter and stellar population in two star-forming regions 0.2 MB
E. H. Nikoghosyan
Abstract. This study aims to compare the properties of interstellar medium in two star-forming regions with different stellar content, with and without high-mass YSOs. The first region is an extended molecular cloud surrounding five IRAS sources: 05168+3634, 05184+3635, 05177+3636, 05162+3639, and IRAS 05156+3643. The second one is a physically connected pair of ultra compact HII regions, G45.07+0.13 & G45.12+0.13, associated with IRAS 19110+1045 and IRAS 19111+1048 sources, respectively. Using these two star formation regions as an example, one can see the relationship between the initial parameters of the parent molecular cloud (hydrogen column density, dust temperature), the process of star formation itself (external triggering shock or independent condensations), and the parameters of the stellar content. High-mass YSOs were obtained only in the G45.07+0.13 & G45.12+0.13 regions, in which, apparently, the initial density of the parent molecular cloud was higher and the star formation process was initiated by an external triggering shock. In addition, in the IRAS 05168+3634 region, there is a relationship between the density of the interstellar medium and the activity of the star formation process. In those subregions, where the mass and density of the initial, parent molecular cloud is greater, the process of star formation is likely to be more active and have a longer duration. In addition, in these sub-groups, on average, the mass of stars is larger.
Some studies on First Byurakan Survey late-type stars 0.4 MB
K. S. Gigoyan
Abstract. Markarian survey (or the First Byurakan Survey, FBS), was the first systematic survey of the extragalactic sky. This objective-prism survey was carried out in 1965-1980 by B. E. Markarian and his colleagues using the 1 m Schmidt telescope of the Byurakan Astrophysical Observatory and resulted in discovery of 1517 UV-excess (Markarian) galaxies. FBS low-resolution spectral plates have been used long period to search and study faint late-type stars (LTSs, M-type and C(carbon) stars) at high galactic latitudes. I will review in this paper the results obtained for late-LTSs using FBS spectral plates. At present the survey is digitized and DFBS database is available. This paper reports also recent new discovered C and M-type stars, and a huge amount of the LTSs candidates selected in the DFBS data base. This paper informed also detecting some amount of the new dwarf carbon (dC) star candidates.
On “Observational Instruments” composed of Stones No. 12, 13 and 14 of “Zorats Qarer” Monument 0.6 MB
H. A. Malkhasyan
Abstract. The work is dedicated to the discussion of some of the stones of the “Zorats Qarer” megalithic monument (No. 12, 13 and 14) in terms of Astronomy. The methods of their use for observational purposes are revealed. Particularly, it has been shown that the stone No. 14 most likely served as a “seating platform” for the observer looking towards the observation angle of the stone No. 13. The other application method has been the formation of the exact direction by the principle of combining the angles of the stones No. 12 and 13. As a result of the usage of the aforementioned methods, three definite directions emerge. The examination of these directions has been performed for the possible date (9000 BC) which is crucial in terms of the origin of the ancient Armenian calendar (Protohaykian), as well as the results of the study of the monument gained so far. The results of the comprehensive examination have been combined with archeological material, Armenian ethnography and folklore. Comparisons have been drawn between days of observing the celestial bodies and important structural units of Protohaykian calendar. At the same time, the observation conditions and the mythological images of the observed stars have been discussed in the context of the most important stages of the cereal cultivation (sowing, harvesting, etc.). Parallels have been drawn with the Armenian religious beliefs (also of other nations), as well as with the results, already known from the study of this monument.
The study of the mentioned stones has revealed that the stars (up to 2m.50 apparent magnitude), observable in 9000 BC, their mythological perceptions, observation conditions and days, are in complete harmony with the structure and content of the Protohaykian calendar (as well as of the ornament-calendar of the early Bronze Age vessel from Keti), and they are closely related to the worship of the Mother Goddess. Links between the observation positions and the definite stages of the cereal cultivation culture (autumn and spring sowing) reappear. There is no contradiction between previously and currently obtained results of the study of the monument. Moreover, the results obtained so far are complementary.
Astronomical Public Activities in Armenia 0.2 MB
M. A. Asryan, S. V. Farmanyan, A. M. Mickaelian
Abstract. The Byurakan Astrophysical Observatory (BAO) founded by the outstanding scientist Viktor Ambartsumian in 1946 is one of the famous astronomical centers in the world, and particularly in the Eurasian area. Along with large scientific, scientific-organizational, and educational activities, public outreach is also very active. The paper gives an overview of BAO public activities in Armenia and in the region. We emphasize the significance of public activities in raising awareness among public on the topics of astronomy and science in general. BAO serves as a regional center for the IAU initiative Astronomy for Development and hosts the IAU South West and Central Asian (SWCA) ROAD, which has a number of activities, including many public ones.
The Evolution of Stars and Astrophysics 0.2 MB
V. A. Ambartsumian (translated by H. A. Harutyunian)
Abstract. Ambartsumian published this article in Russian 75 years ago. In this work, he showed for the first time that star formation was not interrupted in the past, but continues in our cosmological time. His conclusion was that at the same time as the old stars, such as the Sun, there are also much younger ones, which are only a few tens of millions of years old. Another important conclusion was that stars are born in groups. The author called the groups of young stars stellar associations. Actually, by publishing this article, Ambartsumian established a new, so-called ”Byurakan concept” of the formation of space objects.