HOMECommunications of the Byurakan Astrophysical Observatory (ComBAO)
Volume 67, Issue 2, December 2020
Introduction 
0.1 MB
Editorial Board
Pages: 147-148
Surveys for active galaxies: discovery and studies 0.2 MB
A. M. Mickaelian, H. V. Abrahamyan, G. M. Paronyan, G. A. Mikayelyan, and M. V.
Gyulzadyan
Pages: 149-158
Abstract. We present surveys and related studies of active galaxies carried out at the Byurakan Astrophysical Observatory (BAO). This was one of the main research subjects at BAO during many years, since mid-1950s, when Viktor Ambartsumian suggested the hypothesis of the activity of the galactic nuclei. A number of surveys and searches for Active Galactic Nuclei (AGN) and other active galaxies were accomplished during 1960s-1980s. Since mid-1990s, our research group carried out new surveys and studies of active galaxies based on the First Byurakan Survey (FBS or Markarian Survey) and then a number of others. Here we also present the recent results of studies on active galaxies (both AGN and Starbursts) by the Extragalactic group of the Byurakan Astrophysical Observatory (BAO) Research Department "Astronomical Surveys". These studies are characterized by multiwavelength approach to statistical analysis of large amount of data obtained in different wavelengths; from X-ray to radio. A fine classification scheme for active galaxies has also been suggested.
Big Data in Astronomy: Surveys, Catalogs, Databases and Archives 0.6 MB
A. M. Mickaelian
Pages: 159-180
Abstract. We present the modern situation in astronomy, where Big Data coming from the Universe put new tasks for catalogizing, storage, archiving, analysis and usage of the scientific information. The two major characteristics of modern astronomy are multiwavelength (MW) studies (from γ-ray to radio, as well as multi-messenger studies, using also neutrinos, gravitational waves, etc.) and Big Data (including data acquisition, storage and analysis). Present astronomical databases and archives contain billions of objects observed in various wavelengths, both Galactic and extragalactic, and the vast amount of data on them allows new studies and discoveries. Astronomers deal with big numbers. Surveys are the main source for discovery of astronomical objects and accumulation of observational data for further analysis, interpretation, and achieving scientific results. We review the main characteristics of astronomical surveys, we compare photographic and digital eras of astronomical studies (including the development of wide-field observations), we give the present state of MW surveys, and we discuss the Big Data in astronomy and related topics of Virtual Observatories and Computational Astrophysics. The review includes many numbers and data that can be compared to have a possibly overall understanding on the studied Universe, cosmic numbers and their relationship to modern computational possibilities.
Detecting shock waves in non-fundamental mode RR Lyrae using large sample of spectra in SDSS and LAMOST 0.2 MB
Xiao-Wei Duan, Xiao-Dian Chen, Li-Cai Deng, Fan Yang, Chao Liu, Anupam Bhardwaj, and Hua-Wei Zhang
Pages: 181-186
Abstract. Steps toward the nature inside RR Lyrae variables can not only improve our understanding of variable stars but also innovate the precision when we use them as tracers to map the structure of the universe. In this work, we develop a hand-crafted one-dimensional pattern recognition pipeline to fetch out the "first apparitions", the most prominent observational characteristic of shock. We report the first detection of hydrogen emission lines in the first-overtone and multi-mode RR Lyrae variables. We find that there is an anti-correlation between the intensity and the radial velocity of the emission signal, which is possibly caused by opacity changing in the helium ionization zone. Moreover, we find one RRd star with hydrogen emission that possibly shows Blazhko-type modulations. According to our discoveries, with an enormous volume of upcoming data releases of variable stars and spectra, it may become possible to build up the bridge between shock waves and big problems like the Blazhko effect in non-fundamental mode RR Lyrae stars.
Properties of ISM in two star-forming regions 0.3 MB
E. Nikoghosyan, N. Azatyan, H. Harutyunian, D. Baghdasaryan, and D. Andreasyan
Pages: 187-192
Abstract. The Hi-GAL provides an opportunity to make a complete and unbiased view of the continuum emission in the Galactic plane in five bands: 70, 160, 250, 350, and 500 μm. Our research focuses on two of star-forming regions. The first one is the molecular cloud, which includes G45.12+0.13 and G45.07+0.13 UCHII regions. Using the Modified blackbody fitting on Herschel images obtained in four bands: 160, 250, 350, and 500 μm, we determined the distribution of N(H2) hydrogen column density and Td dust temperature. The maps of N(H2) and Td show that UCHII regions clearly stand out against the general background of the molecular cloud with a relatively low density (from 1.0 x 1023 to 3.0 x 1023 cm-2) and significantly higher temperature (up to 100 K), what is fully consistent with the basic concept of UCHII regions about the presence of a hot, high mass stellar source and stellar wind, which leads to the blowing out of matter. The second one is the elongated star-forming region, which includes five stellar subgroups around IRAS 05184+3635, 05177+3636, 05168+3634, 05162+3639 and 05156+3643 sources. Here, on the contrary, the N(H2) is noticeably higher (from 1.0 x 1023 to 5.0 x 1023 cm-2) than in the surrounding molecular cloud and the Td does not exceed 25 K.
Uncertainties of the solar wind in-situ velocity measurements 0.1 MB
G. Gogoberidze and E. Gorgaslidze
Pages: 193-197
Abstract. We study spectral features of Alfvénic turbulence in fast solar wind. We propose a general, instrument independent method to estimate the uncertainty in velocity fluctuations obtained by in-situ satellite observations in the solar wind. We show that when the measurement uncertainties of the velocity fluctuations are taken into account the less energetic Elsasser spectrum obeys a unique power law scaling throughout the inertial range as prevailing theories of magnetohydrodynamic turbulence predict.
M Giants found in the First Byurakan Spectral Sky Survey data base. V. GAIA DR2 data 0.4 MB
K. Gigoyan
Pages: 198-205
Abstract. In this paper we study bright M{type giants found in the First Byurakan Survey (FBS) low-resolution (lr) spectroscopic data base. Phase dependence light-curves from large sky area variability data bases such as Catalina Sky Survey (CSS) and All-Sky Automated Survey for Supernovae (ASAS-SN), and the second Gaia data release data (Gaia DR2) high-quality photometric data are analyzed to estimate some important physical parameters for 1096 M-type giants found at high Galactic latitudes. Their Gaia DR2 broad-band G magnitudes are in the range 8.0 < G < 16.0 mag. Gaia DR2 radial velocities (RV) are available for 134 and luminosities for 158 stars out of 1096. The Gaia DR2 color/absolute magnitude diagram (CaMD), their Galactic distribution, also some other diagrams based on Gaia DR2 photometric data are presented. Absolute magnitudes cover the range +1.0 > M(G) > -5.4 mag. They follow to the behaviors and occupy the same regions on the color-magnitude diagrams studied in many papers by different researches for long period variables (LPVs). Particularly, we consider the locations of the FBS giants on the new diagrams, using multi-band approaches in combination with Wesenheit functions, obtained recently by Lebzelter and colleagues (2018) for the oxygen-rich (O-rich) and carbon-rich (C-rich) LPVs in the Large Magellanic Cloud. Period-Luminosity (P-L) diagram was presented for 112 M Mira-variables. The upper limit of the initial stellar masses can be estimate near 5 Msun for M giants according to the new diagnostic tools. The kinematic properties, space distribution also more interesting cases among the sample were considered.
Investigation of faint galactic carbon stars from the First Byurakan Spectral Sky Survey. IV. GAIA DR2 data 0.2 MB
G. R. Kostandyan
Pages: 206-210
Abstract. The second Gaia data release (Gaia DR2) data are used to analyze and estimate some important parameters for 127 carbon (C) type stars (56 are late N - type Asymptotic Giant Branch (AGB) C stars, 71 are early type CH giants) detected on the First Byurakan Spectral Sky Survey (FBS) low-resolution (lr) spectral plates. Gaia DR2 G broad band magnitudes are in the range 9.4m < G < 18.2m. for FBS C stars. Radial velocities (RV) is available for 75 C stars out of 127. For 9 objects RV is greater than 200 km/s. Absolute magnitudes in V band are estimated for 18 FBS C stars, having luminosity data, from which 17 are CH giants. They are in the range between -3.5m ≤ MV < +0.5m. For FBS 1918+869 absolute magnitude MV = -3.4(±0.2)m, which is typical for N type AGB C stars. Having distance estimations, the Hertzsprung-Russell diagram (HRD, or color - absolute magnitude diagram) was constructed for C stars. All FBS detected C stars are giants and AGB stars in the Galactic Halo. They are not far than 14 kpc from the Sun and 8 kpc from the Galactic plane.
Stellar population in two star-forming regions 0.3 MB
N. Azatyan, E. Nikoghosyan, H. Harutyunian, D. Baghdasaryan, and D. Andreasyan
Pages: 211-218
Abstract. Our research focuses on the stellar content of two star-forming regions. The first one is the molecular cloud which includes G45.12+0.13 and G45.07+0.13 UCHII regions around IRAS 19111+1048 and 19110+1045 sources, respectively. Based on infrared photometric data, we identified a rich stellar population, which includes 909 YSOs with different evolutionary stages. Among selected YSOs there are ZAMS objects. The second one is an elongated molecular cloud, which includes IRAS 05184+3635, 05177+3636, 05168+3634, 05162+3639, and 05156+3643 sources. We identified 1224 candidates of YSOs in the molecular cloud with different evolutionary stages. Selected YSOs are mostly younger then 0.1Myr. The distribution of selected YSOs in both star-forming regions shows that there are dense clusters in the vicinity of all IRAS sources.
Properties of Broad and Narrow Line Seyfert galaxies selected from SDSS 0.3 MB
Vivek Kumar Jha, Hum Chand, and Vineet Ojha
Pages: 219-226
Abstract. A comparative study of a representative sample of Broad and Narrow line Seyfert galaxies is presented. These galaxies have been selected from the 16th data release of the Sloan Digital Sky Survey (SDSS-DR16). Some of the properties derived from single epoch spectrum vary significantly between the two populations. We find that the emission regions of Narrow line Seyfert galaxies are rich in iron content and the accretion rate is higher compared to the Broad line Seyfert galaxies. In our analysis, the H emission line is found to be asymmetric in few of the galaxies with more number of Narrow-line Seyfert 1 (NlSy1) galaxies showing blue asymmetries i.e. traces of outflowing gas as compared to the Broad-line Seyfert 1 (BlSy1) galaxies. This behaviour may be explained by the higher iron content present in the emission line regions of NlSy1 galaxies.
Temperature spectrum of the solar wind turbulence 0.1 MB
G. Gogoberidze, G. Machabeli, and Yu. Voitenko
Pages: 227-231
Abstract. We show that there exists apparent contradiction between the temperature spectra derived from the Spektr-R data and the temperature spectra predicted theoretically. We show that the temperature fluctuations can be correctly estimated from the Spektr-R data only if the mean temperature is isotropic. Since the mean temperature in the solar wind is usually anisotropic, the derived fluctuations appear to be pseudo-temperature rather than temperature. These pseudo-temperature fluctuations are driven by the high-amplitude magnetic fluctuations in Alfvén waves rather than the fluctuations of temperature or thermal velocity.
INT monitoring survey of Local Group dwarf galaxies: star formation history and chemical enrichment 0.2 MB
T. Parto, Sh. Dehghani, A. Javadi, E. Saremi, J. Th. van Loon, and 10 more coauthors
Pages: 232-235
Abstract. The Local Group (LG) hosts many dwarf galaxies with diverse physical characteristics in terms of morphology, mass, star formation, and metallicity. To this end, LG can offer a unique site to tackle questions about the formation and evolution of galaxies by providing detailed information. While large telescopes are often the first choices for such studies, small telescope surveys that perform dedicated observations are still important, particularly in studying bright objects in the nearby universe. In this regard, we conducted a nine-epoch survey of 55 dwarf galaxies called the "Local Group dwarf galaxies survey" using the 2.5m Isaac Newton Telescope (INT) in the La Palma to identify Long-Period Variable (LPV) stars, namely Asymptotic Giant Branch (AGB) and Red Super Giant (RSG) stars. AGB stars formed at different times and studying their radial distribution and mass-loss rate can shed light on the structure formation in galaxies. To further investigate the evolutionary path of these galaxies, we construct their star formation history (SFH) using the LPV stars, which are at the final stages of their evolution and therefore experience brightness fluctuations on the timescales between hundred to thousand days. In this paper, we present some of the results of the Local Group dwarf galaxies survey.
Observational Data Related to the Largest Galaxies of the Universe: What they Tell? 0.1 MB
H. A. Harutyunian
Pages: 236-240
Abstract. The physical mechanism of interaction between dark energy and ordinary baryonic matter is used to show that Ambartsumian's cosmogonic paradigm on the galaxy formation gets new support. This mechanism is considered to compare the cD galaxies observational properties with the model predictions in the framework of the suggested paradigm.
The most evolved sources in the Hi-GAL survey 1.7 MB
D. Elia
Pages: 241-250
Abstract. Far-infrared and submillimetre surveys as the Herschel Galactic Plane Infrared Survey (Hi-GAL) represent an irreplaceable knowledge base about early phases of star formation, permitting statistical analysis based on thousands of Galaxy-wide distributed sources. Those with a regular spectral energy distribution in the Herschel wavelength range 70-500 μm span a variety of evolutionary stages, from quiescent to star forming clumps and, within the latter class, from mid-infrared dark clumps to sources appearing very bright also at shorter wavelengths (e.g. Spitzer 24 μm). A fraction of these clumps hosts the formation of high mass stars, which are expected to reach the zero-age main sequence and to develop a HII region in their surroundings while they are still embedded in their parental large-scale dusty envelope. This paper aims at selecting and studying in detail a robust sample of Hi-GAL clumps supposed to be candidate to host a HII region in their interior. They are expected to be the most evolved sources in the Hi-GAL catalogue. The Galactic locations and the physical properties (temperature, mass, bolometric luminosity and temperature, and surface density) of these sources are discussed here. The large number (1199) of selected sources constitutes an important starting point for planning further interferometric programs, aimed at resolving possible cores hosting a young high-mass star.
Astroinformatics: Statistically Optimal Approximations of Near-Extremal Parts with Application to Variable Stars 0.3 MB
I. L. Andronov, K. D. Andrych, L. L. Chinarova, and D. E. Tvardovskyi
Pages: 251-256
Abstract. The software MAVKA is described, which was elaborated for statistically optimal determination of the characteristics of the extrema of 1000+ variable stars of different types, mainly eclipsing and pulsating. The approximations are phenomenological, but not physical. As often, the discovery of a new variable star is made on time series of a single-filter (single-channel) data, and there is no possibility to determine parameters needed for physical modelling (e.g. temperature, radial velocities, mass ratio of binaries). Besides classical polynomial approximation "AP" (we limited the degree of the polynomial from 2 to 9), there are realized symmetrical approximations (symmetrical polynomials "SP", "wall-supported" horizontal line "WSL" and parabola "WSP", restricted polynomials of non-integer order based on approximations of the functions proposed by Andronov (2012) and Mikulasek (2015) and generally asymmetric functions (asymptotic parabola "AP", parabolic spline "PS", generalized hyperbolic secant function "SECH" and "log-normal-like" "BSK"). This software is a successor of the "Observation Obscurer" with some features for the variable star research, including a block for "running parabola" "RP" scalegram and approximation. Whereas the RP is oriented on approximation of the complete data set. MAVKA is pointed to parts of the light curve close to extrema (including total eclipses and transits of stars and exoplanets). The functions for wider intervals, covering the eclipse totally, were discussed in Andronov (2017). Global and local approximations are reviewed in Andronov (2020). The software is available at http://uavso.org.ua/mavka and https://katerynaandrych.wixsite.com/mavka. We have analyzed the data from own observations, as well as from monitoring obtained at ground-based and space (currently, mainly, TESS) observatories. It may be used for signals of any nature.
Narrow-Band Survey of Star Forming Regions 0.4 MB
T. A. Movsessian, T. Yu. Magakian, S. N. Dodonov, and H. R. Andreasyan
Pages: 257-263
Abstract. We present the results of a narrow-band H and [S II] imaging survey of the star-forming regions in Galaxy. Main tasks of this survey are the search and the studies of the new Herbig-Haro objects and collimated outflows, which are the main indicators of active processes of star formation. Besides, the eruptive stars of very rare types: FUors, EXors, UXors will be searched as well. As the main targets of this survey the R associations, young stellar objects associated with compact reflection nebulae as well as the deeply embedded infrared sources in molecular clouds are selected. Observations are performed with 1-m Schmidt telescope at Byurakan Observatory, which is equipped with modern CCD detector. We plan to significantly expand the list of HH objects by using the high quantum efficiency of this system as well as the telescope's high focal ratio (F/2), which allows detecting low surface brightness objects, and its large field of view.
Big Data: Behind the Scenes 0.1 MB
Kaustubh Vaghmare
Pages: 264-266
Abstract. The phrase \big data" has become a highly common phrase in recent times. However, the phrase `big data', while it may have been coined to indeed vaguely refer to large volumes of data, has now evolved to mean something much more specific. The phrase 'big data' actually refers to a family of technologies, platforms, software and techniques aimed at solving a variety of problems otherwise untenable through conventional or traditional solutions. The present article summarizes a traditional approach to a data management problem and presents limitations of this approach. The three `Vs' used to characterize and define `big data' are then elucidated upon. Finally, the article summarizes commonly used tools and technologies to solve the `big data' problem.
The Origin of LAMOST J1109+7459 0.3 MB
Yazan Khrais and Nour Aldein Almusleh
Pages: 267-271
Abstract. We report a comprehensive Chemo-dynamical analysis of LAMOST J1109+0754, a relatively bright (V = 12.8), extremely metal-poor ([Fe/H] = -3.17), and prograde (JΦ and VΦ > 0) star, with a strong r-process enhancement ([Eu/Fe] = +0.94 ± 0.12, [Ba/Fe] = -0.52 ± 0.15). 31 chemical abundances (from Lithium to Thorium) were derived. We suggest a possible progenitor with stellar mass of 13.4-29.5Msun. We argue that J1109+0754 is representative of the main r-process component due to the well agreement with the scaled-solar r-process component. We analyze the orbital history of this star in a time-varying Galactic potential, based on a Milky-Way analogue model extracted from Illustris-TNG simulations. Using this model, we carry out a statistical estimation of the phase-space coordinates of J1109+0754 at a young cosmic age. Collectively, the calculated motions, the derived chemistry, and the results from the cosmological simulations suggest that LAMOST J1109+0754 most likely formed in a low-mass dwarf galaxy, and belongs to the Galactic outer-halo population.
Stellar and interstellar parameters from large photometric surveys 0.3 MB
O. Malkov, S. Karpov, D. Kovaleva, J. Murthy, S. Sichevsky, and 4 more coauthors
Pages: 272-280
Abstract. The parameterization of stars is a well-known problem and used for various purposes in astronomy. We have shown that multicolor photometric data from large modern surveys can be used for parameterization of stars. With sufficiently good quality photometry, one may compute a 3D extinction map by comparing catalogued multicolor photometry with photometry derived from the secondary estimators such as the distance modulus and the interstellar extinction law with suitable calibration tables for absolute magnitudes with reasonable spectral types, extinctions and distances.
Biermann battery mechanism and its role in evolution of astrophysical magnetic fields 0.1 MB
E. A. Mikhailov and R. R. Andreasyan
Pages: 281-285
Abstract. Nowadays it is well-known that a wide range of astrophysical objects have large-scale magnetic fields. Their observations are usually carried using Faraday rotation measurements. One of the possible mechanisms of their generation (at least the seed ones) can be connected with the Biermann battery mechanism. It is connected with difference between masses of protons and electrons, which are interacting with the cosmic medium. They produce the circular currents which can be generate the magnetic field which is perpendicular to the rotation plane. Here we present the mechanism of the magnetic field generation by the Biermann mechanism in the disc objects which can be useful for galaxies, accretion discs and another objects. One of the important features is connected with the influence of the existing magnetic fields (which can be induced by another charged particles) while studying the movement of the particles.
Catalogs of celestial bodies from digitized photographic plates of the Ukrainian Virtual Observatory Archive 0.7 MB
Y. Protsyuk , I. Vavilova , V. Andruk , L. Pakuliak, S. Shatokhina, and O. Yizhakevych
Pages: 286-292
Abstract. The Ukrainian Virtual Observatory (UkrVO, http://ukr-vo.org) database is compiled from observations conducted in 1898-2018 at observational sites of 8 Ukrainian observatories with about 50 instruments. Now the UkrVO archive covers data of about 40,000 astroplates, from which 15,000 are digitized at three observatories: Main Astronomical Observatory of the NAS of Ukraine (MAO NASU), Research Institute 'Mykolaiv Astronomical Observatory' (RI MAO), and Astronomical Observatory of the Taras Shevchenko National University of Kyiv (AO TSNU). Astroplates were digitized using EpsonTM and MicrotekTM commercial scanners with 16-bit gray levels and resolution of 1200-1600 dpi. Images of all objects registered on plates were processed using the advanced software complex for CCD images' treatment MIDAS/ROMAFOT in the LINUX environment. Additional software modules developed and implemented at the MAO NASU and RI MAO provide both the digitized images' processing and the final products as the catalogs of positions and stellar magnitudes of all the registered objects. The processing of the digitized Northern Sky Survey observations (the FON project) resulted in a few catalogs of coordinates and B-magnitudes for more than 19 million stars and galaxies from the FON-Kyiv part and more than 13 million objects from the FON-Kitab part. Besides, based on these data, two catalogs for more than 5,000 positions and B-magnitudes of asteroids were compiled. Now, in cooperation with Hissar Astronomical Observatory (Dushanbe, Tajikistan), we are preparing similar catalogs based on digitized observations of the third part (1985-1992) of the FON project. The digitized data of open star clusters in UBVR color bands obtained at the Baldone observatory (Latvia) were used to enhance the photometric content of the resulted catalogs. The developed methods of digitization, image processing, and reduction with the latest reference catalogs allowed us to achieve good positional and photometric accuracy of objects. Other digitized data of photographic observations stored in UkrVO archives formed the basis of several Solar System Bodies positional catalogs. The compiled catalogs of 90 positions and B-values of Pluto, 1500 positions of satellites of outer planets are available on the UkrVO website and in the Strasbourg Data Center.
BAO plate archive project: digitization, electronic database and scientific usage 0.3 MB
A. M. Mickaelian, K. S. Gigoyan, G. A. Mikayelyan, G. M. Paronyan, M. V. Gyulzadyan, and G. R. Kostandyan
Pages: 293-301
Abstract. Observational archives are the main source for most of the astronomical studies, as given observations cannot entirely solve any problem and need to be complemented by related observing data both for construction of the time domain, multiwavelength, multi-technique and multi-method picture. This relates to both modern observations and historical ones preserved at many observatories. Therefore, digitization and accessibility of all possible data are rather important. The Byurakan Astrophysical Observatory (BAO) Plate Archive consists of some 37,500 photographic plates and films, obtained with 2.6m telescope, 1m and 0.5m Schmidt telescopes and other smaller ones during 1947-1991 and then by digital methods since 1996. Its most important part, the famous Markarian Survey (or the First Byurakan Survey, FBS) 1874 plates were digitized in 2002-2007 and the Digitized FBS (DFBS, www.aras.am/Dfbs/dfbs.html) was created. New science projects have been conducted based on this low-dispersion spectroscopic material. Several other smaller digitization projects have been carried out as well, such as part of the Second Byurakan Survey (SBS) plates, photographic chain plates in Coma, where the blazar ON 231 is located and 2.6m film spectra of FBS Blue Stellar Objects. However, most of the plates and films were not digitized. In 2015, we have started a project on the whole BAO Plate Archive digitization and its scientific usage. It was aimed at digitization, extraction and analysis of archival data and building an electronic database and interactive sky map. Armenian Virtual Observatory (ArVO, www.aras.am/Arvo/arvo.htm) database will accommodate all new data. The project runs in collaboration with the Armenian Institute of Informatics and Automation Problems (IIAP) and continued during 4 years in 2015-2018. Later on, the project was renovated for 2020-2021. The final result will be an Electronic Database and online Interactive Sky map to be used for further research projects. ArVO will provide all standards and tools for efficient usage of the scientific output and its integration in international databases.
Evolving the VO: from interoperable data collections to an integrated system of services for data-intensive science usage 0.3 MB
F. Pasian, M. Molinaro, and G. Taffoni
Pages: 302-310
Abstract. The Virtual Observatory (VO) represents a successful international enterprise providing interoperability of data collections, thus allowing the possibility of multi-frequency and multi-messenger research. The Big Data era, that astrophysics has stepped into, is forcing scientists to perform data-intensive research. This new concept requires an evolution of the VO concept to provide additional services, in order to transform the VO: from sets of interoperable data to an integrated system of services capable of supporting data-intensive science.
FSR19 and FSR25 confirmed as two new faint and metal-rich globular clusters in the galactic bulge 0.3 MB
C. Obasi, M. Gómez, D. Minniti, and J. Alonso-García
Pages: 311-315
Abstract. We combined the near-IR photometry from the VISTA Variables in the Vía Láctea extended Survey (VVVX) with Gaia EDR3 catalog to study some properties of FSR19 and FSR25. These are confirmed to be low luminosity metal-rich bulge globular clusters (Obasi et al. 2020). The proper motions (PM) remain unchanged and the Color magnitude diagrams (CMD) are consistent with what we previously reported and the red giant branches are narrower than the field.
The Armenian Virtual Observatory (ArVO) 0.4 MB
A. M. Mickaelian, H. V. Astsatryan, A. V. Knyazyan, G. A. Mikayelyan, Gh. Gevorgyan, and 2 more coauthors
Pages: 316-322
Abstract. The Astrophysical Virtual Observatories (AVOs) have been created in a number of countries using their available databases and current observing material as a collection of interoperating data archives and software tools to form a research environment in which complex research programs can be conducted. Among all these data, a large spectroscopic database for all objects is especially useful. The Armenian Virtual Observatory (ArVO) has being created to utilize the Digitized First Byurakan Survey (DFBS) as an appropriate spectroscopic database. ArVO is a project of the Byurakan Astrophysical Observatory (BAO) aimed at construction of a modern system for data archiving, extraction, acquisition, reduction, use and publication. ArVO is based on DFBS and is the Armenian contribution to the International Virtual Observatories Alliance (IVOA). One of the ArVO's main tasks is to create and utilize a global Spectroscopic Virtual Observatory, which will combine data from DFBS and other low-dispersion spectroscopic databases, as well as provide the first understanding on the nature of any object up to B=18 m. In frame of ArVO, BAO collaborates with the Institute of Informatics and Automation Problems (IIAP) of the Armenian National Academy of Sciences to develop software for ArVO corresponding to the IVOA standards. Beside the DFBS, ArVO is being complemented by the Digitized Second Byurakan Survey (SBS) database, the Byurakan photographic archive, and BAO 2.6m and 1m Schmidt telescope observations, and will be a part of IVOA.
Resurrecting DFBS into the Virtual Observatory 0.3 MB
M. Demleitner, A. Knyazyan, D. Baghdasaryan, G. Mikayelyan, and A. Mickaelian
Pages: 323-328
Abstract. The Digitized First Byurakan Survey has digitized and processed about 1900 photographic plates from the objective prism surveys conducted in Byurakan by Benjamin Markarian and collaborators in the 1960ies and 1970ies. After digitization, a custom web service was built and operated first in Rome, then in Trieste. However, as astronomical data systems and standards evolved, it became desirable to update the data and build standards-compliant, Virtual Observatory services from it. This contribution reports on the challenges encountered during this migration, the solutions we chose, and the lessons to be learned. It also discusses the use of the resulting services.
Asteroid Detection using Machine Learning Algorithm 0.2 MB
L. V. R. Chaitanya Prasad, T. Anjali Shivani Reddy, and Bhuvaneshwari Kashi
Pages: 329-334
Abstract. My paper starts from the question many of us wonder `What if an Asteroid hit Earth? The answer depends on how big an asteroid is in terms of dimension- Let's say an asteroid of baseball ground hits earth, which can completely erase a city. Most of the asteroids are detected by Satellites, Probes and telescopes with large aperture length. Mostly large Telescopes from earth are used for tracking main belt asteroid but what if it gets out of sight from researchers or Scientists; it might take away peoples life. In this paper, I introduced machine learning to detect the asteroid with more than 60 percent of efficiency. The famous Scientist Stephen Hawking wrote in his last book that `Asteroids are great threatened to the planets'. Machine learning being a one of the best predictive method without explicitly giving any external command. In this paper, I attempt to introduce new machine learning algorithm in the replacement of Astrometrica software with Pan-Starr Telescope real-time Fits file data which is located in Hawaii, USA.
Infrared study of IRAS 18316-0602 star-forming region 0.2 MB
D. Andreasyan, N. Azatyan, E. Nikoghosyan, H. Harutyunian, and D. Baghdasaryan
Pages: 335-337
Abstract. We present the results of the investigation of ISM and the young stellar population in the IRAS 18316-0602 star-forming region which is referred to as UCHII (G25.65+1.05). Single temperature modified blackbody model shows that values of N(H2) hydrogen column density and Td dust temperature are in ranges 2 - 7 x 1023 cm-2 and 12 - 30 K, respectively. The analysis of infrared photometric data allowed to reveal about 50 young stellar objects in the G25.65+1.05 UCHII region.
Runaway stars in Vel OB1 association 0.1 MB
N. Azatyan, L. Kaper, D. Guo, and E. Nikoghosyan
Pages: 338-340
Abstract. We present the origins of two runaway stars in the Vel OB1 association using Gaia proper motions and parallaxes. Proper motions and parallaxes show that mentioned two runaways came out from Vel OB1 association: one of them, namely CD-41 4637 is the result of dynamical interaction in its host cluster and Vela X-1 high-mass X-ray binary became a runaway after supernova explosion.
Detailed Studies of Radiogalaxy Mrk1032 0.2 MB
S. A. Hakopian, S. N. Dodonov, and R. R. Andreasyan
Pages: 341-343
Abstract. The first results of the observations of Mrk1032, conducted with the 6-m telescope of SAO Russia, are given. It is shown, in particular, that a large complex of HII-regions, revealed by the integral-field spectroscopy, is the main source of UV radiation in the galaxy.
Multiple asteroid systems from the UkrVO digitized photographic plates 0.1 MB
L. Kazantseva and S. Shatokhina
Pages: 344-346
Abstract. Several catalogs of various celestial objects were compiled based on the processing of Ukrainian VO archives and observatories in Kitab (Uzbekistan) and Baldone (Latvia). We analyzed the catalogs of asteroid positions and B-magnitudes obtained from the processing of digitized photographic plates and selected from them asteroids, which are known as multiple. Positional observations cover the period 1973-1993 and may be useful for a more detailed study of the dynamics of these systems. The obtained photometric characteristics of asteroids will be useful for studying changes in brightness.
Stellar spectra analysis of giant stars: ARCTURUS 0.1 MB
M. Rah
Pages: 347-348
Abstract. In this study, we analyzed the evolved red giant ARCTURUS using high-resolution spectroscopy that was taken by HARPS. The other names of this star is α Boo - Arcturus - HR 5340 - HD 124897 - HIP 69673. This evolved (log g = 1.66 dex) star shows low metallicity nature ([Fe/H] = -0.52), which could be employed to study the chemical evolution of the early universe.
The Early-phase Distribution of the Milky Way Using K-giant Stars from LAMOST DR5 0.5 MB
A. Taani
Pages: 349-350
Abstract. With the advent of large astronomical surveys, the need of identification of the most interesting astrophysical object is required. In this work we focus on extracting red giant metal-poor stars from the LAMOST DR5. We then query the 5-D space coordinates from the Gaia DR2 to investigate their energy-action space. This sample will be used for studying the chemical and dynamical evolution of the early galactic phase. Also, identifying stars with kinematical similarities would enable us to trace the galactic assembly.
From Evolved Stars to the Formation and Evolution of NGC 6822 0.1 MB
Sima Taefi Aghdam, Elham Saremi, and Atefeh Javadi
Pages: 351-353
Abstract. NGC6822, an isolated dwarf irregular galaxy (dIrr), due to close distance, apparent isolation, and easy observation, has been always selected as a desired candidate for studying star formation and galactic evolution, without the strong gravitational influences of other systems. To derive the SFH of NGC6822, the method mentioned by Javadi et al. (2011) is used which is based on theoretical models coupled with color-magnitude diagrams (CMDs) by using directly the long period variable (LPV) stars which are mostly asymptotic giant branch (AGB) stars at their very late stage of evolution, as well as more massive red super-giant (RSG) stars according to their significant role to study the star formation rate (SFR). To calculate the SFH in the bar of the galaxy, we use more than 600 LPV stars from different catalogs of variable stars that two of the most important are Whitelock et al. (2013) and Letarte et al. (2002) that they reported the main part of the LPVs and the Carbon stars, respectively, Patrick et al. (2015) announced the RSG stars. Understanding the star formation history of NGC 6822 plays an important role in comparing the galaxy history evolution with other nearby dwarf galaxies as well as studying the nature of the evolving population of galaxies which were detected in deep redshift surveys.
Deep Convolutional Neural Networks models for the binary morphological classification of SDSS-galaxies 0.2 MB
M. Vasylenko, D. Dobrycheva, V. Khramtsov, and I. Vavilova
Pages: 354-358
Abstract. We present the deep learning approach for the determination of morphological types of galaxies. We demonstrate the method's performance with the redshift-limited (z < 0.1) training sample of 6 163 galaxies from the SDSS DR9. We exploited the deep convolutional neural network classifiers such as InceptionV3, DenseNet121, and MobileNetV2 to process images of SDSS-galaxies (100x100 pixels, 25 arcsec in each axis in size) using g, r, i filters as R - G - B channels to create images. We provided the data augmentation (horizontal and vertical flips, random shifts on ±10 pixels, and rotations) randomly applied to the set of images during learning, which helped increase the classifier's generalization ability. Also, two different loss functions, MAE and Lovasz-Softmax, were applied to each classifier. The target sample galaxies were classified into two morphological types (late and early) trained on the images of galaxies from the sample. It turned out that the deep convolutional neural networks InceptionV3 and DenseNet121 with MAE-loss function show the best result attaining 93.3% accuracy.
In memory of Artur S. Amirkhanian 0.1 MB
Page: 359