Byurakan Survey Research Articles

The digitized First Byurakan Survey database. New carbon stars confirmed

Some amount of the new carbon ( C ) stars was confirmed among the sample of the Late-Type Stars (LTSs) candidates, selected on the Digitized First Byurakan Survey (DFBS) spectral plates. The DFBS is the digitized version of the First Byurakan Survey (FBS, or Markarian survey). The 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 colleagues using the 1 m Schmidt telescope of the Byurakan Astrophysical Observatory. In this work we present Gaia DR3 photometric data, spectra, light curves, distances, high above/below Galactic plane, radial velocities (RV), and other important physical characteristics from modern astronomical catalogues for some amount new confirmed DFBS carbon stars. The confirmation is based on Gaia DR3 BP/RP low-resolution spectral database. In previous studies of the DFBS plates, these objects were presented as LTSs candidates. Some objects are located more than 7 kpc from the Galactic plane. Four of them are N-type C stars, from which two are Mira-type variables. The remaining objects are CH-type giants at high Galactic latitudes. Most probably they present binary systems.

The Digitized First Byurakan Survey Database. Late-type stars candidates. New confirmations

More than 3000 Late-Type Stars (LTS) candidates was confirmed among the sample, selected on the Digitized First Byurakan Survey (DFBS) spectral plates. The DFBS is the digitized version of the First Byurakan Survey (FBS, or Markarian survey). This objective-prism survey was carried out in 1965- 1980 by B. E. Markarian and colleagues using the 1 m Schmidt telescope of the Byurakan Astrophysical Observatory (BAO). FBS spectral plates have been used long period to search and study faint LTS (Ctype (carbon) and M-type) stars at high Galactic latitudes. Thousands of objects was confirmed as LTS. The confirmation is based on Gaia DR3 BP/RP low-resolution spectral database. In previous studies of the DFBS plates, these objects were presented as LTS candidates. Some objects are located more than 10 kpc. The predominant part of the new confirmed objects are M dwarfs.

X-ray AGM activity classes based on SDSS spectra

Sources of X-ray radiation are very interesting and at the same time little studied. Their class mainly includes objects that exhibit a certain activity, such as AGNs, cataclysmic variable stars, white dwarfs, pulsars, etc. Identification of X-ray sources is a rather difficult task, and it is not always possible to detect an optical object. In this work, we tried to carry out a spectral classification of X-ray AGNs and identify activity classes, taking as a basis the ROSAT BSC/FSC catalog of X-ray AGNs, compiled on the basis of low-dispersion spectral plates of the first Byurakan survey. We identified these objects with the SDSS spectral catalog and tried, by carefully studying the spectra, to find out their activity classes, as well as to understand which activity class is more common in these sources.

New M dwarfs found in DFBS plates

In this paper we report about 100 new M dwarfs, confirmed in the DFBS database. The DFBS is the digitized version of the First Byurakan Survey (FBS, or Markarian survey). FBS plates have been used to search and study faint Late-Type Stars (LTS). The confirmations is based on Gaia DR3 BP/RP spectral database. In previous studies of the DFBS plates, these objects were presented as LTS candidates. TESS phased light curves for some of them shows flares. In SEDs of these objects the infrared excess is clearly visible.

Homogeneous fine classification of Markarian galaxies based on SDSS medium-resolution spectroscopy

Context. Markarian (Mrk) galaxies, revealed due to their ultraviolet excess are very famous; they play a significant role in many astro-physical problems and come in a variety of types: Seyferts (Sys), low-ionization narrow emission-line regions (LINERs), starbursts (SBs), blue compact dwarf galaxies (BCDGs), as well as some quasars (QSOs) and blazars. They also appear as sources of non-optical radiation, such as gamma-ray, X-ray, ultraviolet (UV), infrared (IR), and radio, including some extremely high-energy gamma-ray sources (Mrk 421, Mrk 501) and very high-luminosity IR galaxies (Mrk 231). Aims. The classifications of Mrk galaxies for activity types have been carried out based on old mostly poor-quality and inhomoge-neous spectra (relatively low-resolution photographic spectra and low S/N spectra). The Sloan Digital Sky Surveys (SDSS) provides ~90% of the existing medium-resolution spectra, and is a relevant homogeneous database for classification of galaxies. Our aim was to obtain homogeneous classifications of Mrk galaxies by means of the SDSS spectra. Methods. Based on our work on the classification of newly revealed objects from various recent catalogs, we developed a fine classification scheme for activity types based on the homogeneous database of the SDSS spectroscopy. This scheme was applied to Mrk galaxies having spectra in the SDSS (779 out of 1544, 50.45%). Results. As a result, 779 Mrk galaxies now have homogeneous optical spectral classification that can be used for further studies and statistics of their physical and spatial properties. We revealed 2 QSOs, 49 classical Seyferts (broad-line Seyferts 1, BLS1s), 17 narrow-line Seyferts 1 (NLS1s), 4 Sy2s, 12 LINERs, 11 active galactic nuclei (AGN) without a definite type, 31 Composite spectrum objects, and 533 HII/Starbursts. Due to low-quality spectra, some objects were left without definite activity types and were classified as emission or absorption galaxies.

M dwarfs found in the first Byurakan spectral sky survey database. Gaia EDR3 and TESS data. Some preliminary results

Abstract In order to gain more information on the 236 M dwarfs identified in the First Byurakan Survey (FBS) low-resolution (lr) spectroscopic database, Gaia EDR3 high-accuracy astrometric and photometric data and Transiting Exoplanet Survey Satellite (TESS) data are used to characterise these M dwarfs and their possible multiplicity. Among the sample of 236 relatively bright $(7.3 < K_S < 14.4)$ M dwarfs, 176 are new discoveries. The Gaia EDR3 G broadband magnitudes are in the range $11.3 < G < 17.1$ . New distance information based on the EDR3 parallaxes are used to estimate the G-band absolute magnitudes. Nine FBS M dwarfs out of 176 newly discovered lie within 25 pc of the Sun. The FBS 0909-082 is the most distant $(r=780$ pc) M dwarf of the analysed sample, with a G-band absolute magnitude $M(G) = 9.18$ , $M = 0.59$ M $_{\odot}$ , $L = 0.13597$ L $_{\odot}$ , and $T_{eff}$ = 3844 K; it can be classified as M1 - M2 subtype dwarf. The nearest is FBS 0250+167, a M7 subtype dwarf located at 3.83 pc from the Sun with a very high proper motion (5.13 arcsec yr $^{-1}$ ). The TESS estimated masses lie in the range 0.095 ( $\pm$ 0.02) M $_{\odot}\leq$ $M\leq$ 0.7 ( $\pm$ 0.1) M $_{\odot}$ and $T_{eff}$ in the range 4000 K < $T_{eff}$ < 2790 K. We analyse colour-colour and colour-absolute magnitude diagram (CaMD) diagrams for the M dwarfs. Results suggest that 27 FBS M dwarfs are double or multiple systems. The observed spectral energy distribution (SED) for some of the M dwarfs can be used to classify potential infrared excess. Using TESS light curves, flares are detected for some FBS M dwarfs. Finally, for early and late sub-classes of the M dwarfs, the detection range for survey is estimated for the first time.

Armenian Virtual Observatory: Status and activities

Among all astronomical data, a large spectroscopic database is especially useful for understanding the nature of all observed objects. 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 for processing complex data-intensive and compute-intensive research workflows. The Armenian Virtual Observatory (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 the Digitized First Byurakan Survey (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=18m. Hence, ArVO will utilize the DFBS as an appropriate large spectroscopic database. In the frame of ArVO, BAO collaborates with the Institute of Informatics and Automation Problems (IIAP) of the National Academy of Sciences of Armenia to develop software ecosystem for ArVO satisfying the IVOA standards. Besides the DFBS, ArVO provides access to the Digitized Second Byurakan Survey (SBS) database, the Byurakan photographic archive, and BAO 2.6 m and 1 m Schmidt telescopes modern observations.

Optical properties of variable radio sources from NVSS and FIRST

We have carried out a number of studies to reveal radio properties of active galaxies, namely AGN and Starbursts. A major work was related to the cross-correlation of NVSS and FIRST radio catalogues and revelation of variable radio sources. Most probably, most of them are extragalactic ones; AGN and Starbursts. We have carried out spectroscopic classification of 6301 of these objects and revealed many Seyferts, LINERs and Starbursts. We have also studied radio properties of VCV-13 AGN, Markarian galaxies and Blazars. One of the aims of our studies is to establish the radio/opt flux ratio limit between normal galaxies detected in radio and radio loud active galaxies. The ultimate goal of these studies is to combine results obtained from radio studies and derived radio properties of active galaxies with gammaray, X-ray, UV, optical, IR and submm/mm to have the overall multiwavelength understanding on these objects.

First Byurakan Spectral Survey. Late-Type Stars. Dwarfs

A total of 18 lists of the First Byurakan Survey of Late-Type Stars (FBSLTS) were published between 1990 and 2016. The stars were found on FBS low-dispersion spectral plates. A systematic search and selection were carried out on a surface of ∼16 000deg2 on almost the whole area of the FBS. Since 2007, all FBS low-resolution spectral plates have been digitized. The second version of the “Revised And Updated Catalogue of the First Byurakan Survey of Late-Type Stars”, containing data for 1471 M and C (carbon) stars (130 C-type giants, 1105 M– giants, and 236 M dwarfs) was generated. Among the 236 M dwarfs selected, 176 are new discoveries. The Gaia EDR3 G broad-band magnitudes are in the range 11.3 < G < 17.1. New distance information by Bailer-Jones et al. (2021), which is based on the EDR3 parallaxes are used to estimate the G-band absolute magnitudes for M dwarfs. 9 FBS M dwarfs (out of 176 new discovered) lie within 25pc of the Sun. The object FBS 0909-082 is more distant (r = 780˙pc) M dwarf among the sample considered, for which G-band absolute magnitude M(G)=9.18, M= 0.59MSun, L=0.13597 LSun, and Teff = 3844 K. This object can be classified as M1-M2 subtype dwarf. The nearest object is FBS0250+167, a M7 subtype dwarf with very high proper motion (5.13 arcsec/yr) and is located at 3.83pc from the Sun. The TESS estimated masses lie in the range 0.095(±0.02)M⊙ ≤M≤0.7(±0.1)M⊙ and Teff in the range 4000K < Teff < 2790K for FBSM dwarfs. Color-absolute magnitude (CaMD) diagrams are constructed for the FBSM dwarfs based on Gaia EDR3 and TESS data.

Some studies on First Byurakan Survey late-type stars

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.

Investigation of DFBS late type stars at high galactic latitudes

We study in this thesis relatively bright late-type giants found in the First Byurakan Survey (FBS) data base. We present the 2nd version of the catalogue of FBS LTS with new data (FBS LTS v2), 1471 objects. It is a homogeneous and complete database for high- Galactic late-type stars, including M and C types. Since 2007, all FBS low-resolution spectral plates are digitized. All DFBS spectral plates are analyzed with FITSView and SAO Image ds9 and numerous relatively faint LTS were discovered. We have made cross-correlation with DFBS, USNO-B1.0, 2MASS, AllWISE, IRAS PSC/FSC, AKARI, ROSAT BSC/FSC, GCVS, SDSS and added updated SIMBAD data. For numerous new detected objects, we present accurate DSS2 positions, approximate spectral subtypes refined from the DFBS low-dispersion spectra, luminosity classes estimated from 2MASS colours, and available proper motions for 1471 FBS LTS. The Revised and Updated Catalogue v2 lists a large number of completely new objects, which promise to extend very significantly the census of M giants, faint N-type AGB carbon stars, CH-type carbon giants at high Galactic latitudes, also M dwarfs in the Solar vicinity up to 16.0m-17.0m in visual. Phase dependent 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 early installment of the third Gaia data release (Gaia EDR3) photometric and astrometric data have been used to characterize our sample of 1100 M-type giants found and 130 C-type stars at high latitudes. We show the behaviour of our sample stars in a Gaia DR2 color–absolute magnitude diagram (CaMD), the Gaia-2MASS-diagram, including two alternative versions, and the logP-K-diagram. In this way we explore the potential of these diagrams and their combination for the analysis and interpretation of datasets of LPVs. We show the possibility to classify stars into M- and C-types and to identify the mass of the bulk of the sample stars.

Search and Studies of the First Byurakan Survey Blue Stellar Objects

The First Byurakan Survey (FBS) 2nd Part was devoted to search and studies of Blue Stellar Objects (BSOs) and Late-type Stars. Eleven lists of 1103 BSOs were published in Astrophysics in 1990-1996, found in FBS low-dispersion spectroscopic plates. The selection was carried out in the region with +33◦ > δ > +45◦ and δ >+61◦ with a surface of ∼4000 deg2. As a result, the catalogue of the FBS BSOs was compiled. Its preliminary version has been available at CDS since 1999. We revised and updated the FBS BSOs catalogue with the new data from recently published optical and multiwavelength catalogues to give access to all available data and make further comparative studies of the properties of these objects possible. We made cross-correlations of the FBS BSOs catalogue with the MAPS, USNO-B1.0, SDSS, and 2MASS, as well as ROSAT, IRAS, NVSS, and FIRST catalogs, added updated SIMBAD and NED data for the objects, and provided accurate DSS1 and DSS2 positions and revised photometry. We also checked the objects for proper motion and variability. A refined classification for the low-dispersion spectra in the Digitized First Byurakan Survey (DFBS) was carried out. The revised and updated catalogue of FBS blue stellar objects contains 1101 objects. The FBS blue stellar objects catalogue can be used to study a complete sample of white dwarfs, hot subdwarfs, HBB stars, cataclysmic variables, bright AGN, and to investigate individual interesting objects.

BAO Plate Archive Project: Recent Results

We present the recent results of the Byurakan Astrophysical Observatory (BAO) Plate Archive Project that is aimed at digitization, extraction and analysis of archival data and building an electronic database and interactive sky map. BAO Plate Archive consists of some 37,000 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, creation of electronic database and its scientific usage. Armenian Virtual Observatory (ArVO, www.aras.am/Arvo/arvo.htm) database will accommodate all new data. The project lasted 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.

The Digitized First Byurakan Survey (DFBS) as UNESCO Documentary Heritage

The famous Markarian Survey (or the First Byurakan Survey, FBS) was carried out in 1965-1980. Its 2000 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. The Armenian Virtual Observatory (ArVO, www.aras.am/Arvo/arvo.htm) database accommodates all new data. The project was conducted in collaboration with the Italian, USA and German scientists, as well as the Armenian Institute of Informatics and Automation Problems (IIAP) and continued during 6 years in 2002-2007. Markarian Survey and its digitized version were included in UNESCO Documentary Heritage “Memory of the World” International Register in 2011 as one of the rare heritage items from science.

Markarian survey and Markarian galaxies

Markarian survey (or the First Byurakan Survey, FBS) was the first systematic survey for active galaxies and was a new method for search for such objects. Until now, it is the largest objective prism survey of the sky (17,000 deg2). It was carried out in 1965-1980 by B. E. Markarian and his colleagues and resulted in discovery of 1517 UV-excess (Markarian) galaxies. They contain many active galaxies, as well as powerful gamma-, X-ray, IR and radio sources (Mrk 180, 231, 421, 501, etc.), BCDGs (Mrk 116) and interacting/merging systems (Mrk 266, 273, etc.). They led to the classification of Seyfert galaxies into Sy1 and Sy2 and the definition of Starbursts (SB). Several catalogs of Markarian galaxies have been published (Bicay et al., 1995, Markarian et al., 1989, Mazzarella & Balzano, 1986, Petrosian et al., 2007) and they are accessible in all corresponding databases. Markarian survey also served as a basis for search for UVX stellar objects (including QSOs and Seyferts), late-type stars and optical identification of IR sources. At present the survey is digitized and DFBS database is available. We review the main characteristics of the Markarian survey, its comparison with other similar surveys and the importance of Markarian galaxies in modern astrophysics.

New results for FBS late-type stars using Gaia EDR3 data

AbstractWe study in this paper bright late-type giants found in the First Byurakan Survey (FBS) data base. Phase dependent 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 early installment of the third Gaia data release (Gaia EDR3) photometric and astrometric data have been used to characterize our sample of 1 100 M-type giants and 130 C-type stars found at high latitudes. Gaia radial velocities (RV) are available for 134 and luminosities for 158 stars out of 1 100. We show the behaviour of our sample stars in a Gaia color–absolute magnitude diagram (CaMD), the Gaia-2MASS-diagram from Lebzelter et al. with some alternative versions. In this way we explore the potential of these diagrams and their combination for the analysis and interpretation of datasets of LPVs. We show the possibility to classify stars into M- and C-types and to identify the mass of the bulk of the sample stars.

Variability study of the FBS M giants

We study in this paper variability of the late-type M giants found in the First Byurakan Survey (FBS) spectroscopic data base. We used phase dependent light – curves from large sky area variability data bases such as Catalina Sky Survey (CSS) and All-Sky Automated Survey for Supernovae (ASAS-SN). We used also the distance information derived from Gaia EDR3 to construct the Galactic distribution of the M – type giants from the second edition of the FBS Late-Type Stars catalogue including various kinds of long period variables.

Features of a Sample of Star-forming Galaxies in two Adjacent SBS Fields

Some results are presented on studies of a sample of about hundred galaxies (“100SBS”) from two adjacent fields of SBS (Second Byurakan Survey), which have spectral data in SDSS (Sloan Digital SkySurvey-www.sdss.org ).The work is carried out as a part of the long-term program (Hakopian, 2013) forin-depth study of the galaxies in seven selected SBS fields (including the two under investigation).Comparative analysis was done between two classifications that the 100SBS objects got - from one side Starburst or Starforming in SDSS, from the other - SfGcont and SfGneb, with a possibility of further detailing in accordance to our scheme for SfG, i.e. star-forming galaxies. Obtained results showed good perspectives in using of our scheme for differentiation of activity phases of SfGs and for better statistics and comprehensive studies. Space distribution of 100SBS galaxies, what is important, homogeneously selected in continuous (32 sq.deg) area, was obtained using uniformly determined in SDSS redshift values. As it follows from the graphs plotted at 0.01 intervals the maximum of the distribution, with an equal number of Staforming and Starburst galaxies falls on the range 0.01<z<;0.019. The minimum of the distribution falls on the range 0.02<z<0.029 and more expressed for Starbursts. Also some difference is discerned in a diversity of morphological appearance of the galaxies composing two neighboring to it intervals.

Absolute magnitudes of white dwarfs and discovery of new white dwarfs from FBS Blue Stellar Objects by means of Gaia EDR3 data

Abstract This article is a presentation of a project which is a statistical study of white dwarfs’ properties carried out based on the sample of the First Byurakan Survey Blue Stellar Objects (FBS BSOs) and the Catalogue of White Dwarfs. Using these results, we have searched and will continue to search for new white dwarfs by means of Gaia accurate astrometry. The discovery and study of new White Dwarfs (WDs) is extremely important for understanding the kinematics and dynamics of the local stellar population. They are evolutionary signatures of the Milky Way, as most of stars pass through this evolutionary stage. We have carried out a statistical analysis of the White Dwarfs Catalogue to establish their average physical properties. Based on these data, we have searched for new WDs using Gaia EDR3 accurate astrometry. It provides huge amount of data to confirm WDs and reveal many more such objects. Gaia’s astrometric accuracy allows more detailed studies of WDs and many other stars. Using Gaia accurate data in combination with SDSS and DFBS low-dispersion spectra and additional multiwavelength data, we have revealed many new WDs. Many of them are subject for studies on binarity and variability (including a number of subtypes, e.g. ZZ Ceti stars (pulsating WDs), cataclysmic variables, etc.). WDs among FBS blue stellar objects at high galactic latitudes have been searched and revealed. Search for high galactic latitude WDs in DFBS have also been carried out. Using the revealed and calculated characteristics, a statistical study of WD properties is being done.

Astronomical objects classification based on the Digitized First Byurakan Survey low-dispersion spectra

Abstract The Digitized First Byurakan Survey is the largest and the first systematic objective-prism survey of the extragalactic sky. The detection, extraction, and classification of about 40 million spectra of about 20 million astronomical objects available in the survey require distinguishing the pixels containing photons from the source and the noise pixels per object. This paper aims at developing a service to classify the spectra of UV-excess galaxies, quasars, compact galaxies, and other objects in the survey. Supervised and unsupervised convolutional neural network deep learning algorithms have been developed and studied.