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Vol 71, No 1 (2016)

Article

Ultra-flat galaxies selected from RFGC catalog. I. The sample properties

Karachentseva V.E., Kudrya Y.N., Karachentsev I.D., Makarov D.I., Melnyk O.V.

Abstract

We used the Revised Flat Galaxy Catalog (RFGC) to create a sample of ultra-flat galaxies (UFG) covering the whole northern and southern sky apart from theMilkyWay zone. It contains 817 spiral galaxies seen edge-on, selected into theUFG sample according to their apparent axial ratios (a/b)B ≥ 10.0 and (a/b)R ≥ 8.53 in the blue and red bands, respectively. Within this basic sample we fixed an exemplary sample of 441 UFG galaxies having the radial velocities of VLG < 10000 km s−1, Galactic latitude of | b |> 10° and the blue angular diameter of aB > 1.′0. According to the Schmidt test the exemplary sample of 441 galaxies is characterized by about (80–90)% completeness, what is quite enough to study different properties of the ultra-flat galaxies. We found that more than 3/4 of UFGs have the morphological types within the narrow range of T = 7± 1, i.e. the thinnest stellar disks occur among the Scd, Sd, and Sdm types. The average surface brightness of UFG galaxies tends to diminish towards the flattest bulge-less galaxies. Regularly shaped disks without signs of asymmetrymake up about 2/3 both among all the RFGC galaxies, and the UFG sample objects. About 60% of ultra-flat galaxies can be referred to dynamically isolated objects, while 30% of them probably belong to the scattered associations (filaments, walls), and only about 10% of them are dynamically dominating galaxies with respect to their neighbours.

Astrophysical Bulletin. 2016;71(1):1-13
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Search for radio transients and recent detection of radio sources in the RATAN-600 surveys of 1980–1994

Zhelenkova O.P., Majorova E.K.

Abstract

In the paper we present the results of search for transient sources using the data from the surveys conducted onRATAN-600 at 7.6 cmin the time period of 1980–1994.We detected three events at a level of 3–5σ. A search for coincidenceswith detected transient events was carried out. Using the data from radio and optical surveys and the VizieR, SIMBAD, and NED databases, we made assumptions on the possible nature of these events. The first transient is probably associated with AGN activity, the second—with a cataclysmic GRB event or with a supernova, the origin of the third is not determined. The inference on the possibility of search for variable sources and transients using the data from the RATAN-600 blind surveys was drawn. Searching for transients, we have found twenty-two radio sources which are associated with the NVSS objects but are not included in the RCR catalog. Three of them turned out to be presumably variable.

Astrophysical Bulletin. 2016;71(1):14-23
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Searching for the birthplaces of open clusters with ages of several billion years

Acharova I.A., Shevtsova E.S.

Abstract

We discuss the possibility of finding the birthplaces of open clusters (OC) with ages of several billion years. The proposed method is based on the comparison of the results of the chemical evolution modeling of the Galactic disk with the parameters of the cluster. Five OCs older than 7 Gyr are known: NGC6791, BH176, Collinder 261, Berkeley 17, and Berkeley 39. The oxygen and iron abundances in NGC6791 and the oxygen abundance in BH176 are twice the solar level, the heavy-element abundances in other clusters are close to the corresponding solar values. According to chemical evolution models, at the time of the formation of the objects considered the regions where the oxygen and iron abundances reached the corresponding levels extended out to 5 kpc from the Galactic center.At present time theOCs considered are located several kpc from the Galactic center. Some of these clusters are located extremely high, about 1 kpc above the disk midplane, i.e., they have been subject to some mechanism that has carried them into orbits uncharacteristic of this type of objects. It follows from a comparison with the results of chemical evolution that younger clusters with ages of 4–5 Gyr, e.g., NGC1193,M67, and others, may have formed in a broad range of Galactocentric distances. Their large heights above the disk midplane is sufficient to suggest that these clusters have moved away from their likely birthplaces. Clusters are carried far away from the Galactic disk until the present time: about 40 clusters with ages from 0 to 2 Gyr are observed at heights ranging from 300 to 750 pc.

Astrophysical Bulletin. 2016;71(1):24-32
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Detailed optical spectroscopy of the B[e] Star MWC17

Klochkova V.G., Chentsov E.L.

Abstract

Based on the material of multiple high-resolution R = 60 000 observations conducted on the 6-m telescope (BTA) of the Special Astrophysical Observatory in combination with the Nasmyth Echelle Spectrograph (NES), we closely studied the features of the optical spectrum of the star MWC17 with the B[e] phenomenon. In the wavelength interval of 4050–6750 Å, we identified numerous permitted and forbidden emissions, interstellar Na I lines, and diffuse interstellar bands (DIBs). Radial velocities were estimated from lines of different origin. As the systemic velocity, Vsys, the velocity of the forbidden emissions can be accepted: −47 kms−1 (relative to the local standard Vlsr = −42 kms−1). Comparison of the obtained data with the earlier measurements allows us to conclude on the absence of considerable variability of spectral details.

Astrophysical Bulletin. 2016;71(1):33-42
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Magnetic field structure and evolution features of selected stars. III.

Glagolevskij Y.V.

Abstract

We present the results of modeling for about a hundred magnetic stars. It is shown that the dipole representation of magnetic field structures describes the distribution of the magnetic field over stellar surfaces fairly well. We analyze some patterns which support the relic hypothesis of magnetic field formation.Arguments are given in favor of the assumption that themain properties ofmagnetic stars—slow rotation, predominant orientation of magnetic field lines along the plane of the rotation equator, complex internal structures of magnetic fields—are acquired in the process of gravitational collapse. There are no conditions for that in the non-stationary Hayashi phase and in the stage of a radiative young star.

Astrophysical Bulletin. 2016;71(1):43-58
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Parameters of superflares on G-Type stars observed with the Kepler space telescope

Savanov I.S., Dmitrienko E.S.

Abstract

We continued the analysis of 279 G-type stars with superflares (energies in the range of 1033–1036 erg). We calculated the SFL parameter (part of the stellar surface which emits in the flare). The SFL estimates were derived from the relation connecting this value with the amplitude of the flare and its radiation on the assumption of the blackbody character of the emission at times close to its maximum. Most SFL values are in the range of 0–0.1, with values of 0.2–0.4 for some strong flares. Dependence of SFL on effective temperature for stars with superflares is similar to that found earlier for the spottedness parameter S. The SFL distribution reaches its maximum in the temperature range of about 5100–5250 K and decreases with the effective temperature increase. We suggested an assumption on the presence of bimodal distribution in the “SFL–rotation period” relation with a gap for objects with rotation periods P of about 10 days. For stars with P less than 10 days, the given data can indicate a decrease in flare areas with the P increase. Our analysis showed that significant changes both in flare energy and in flare areas can be achieved with small changes in spottedness S for one and the same star.

Astrophysical Bulletin. 2016;71(1):59-63
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Spectrometric and photometric study of the eclipsing variable AM Leo

Gorda S.Y.

Abstract

The results of quasi-simultaneous spectroscopic and photometric observations of a W UMatype eclipsing variable star AM Leo are presented. The observations were carried out with a 1.2-m telescope equipped with a high-resolution echelle spectrometer, and a telescope-reflector (D = 0.45m) of the Kourovka Astronomical Observatory of Ural Federal University. New values of semi-amplitudes of the radial velocity curves of the components, K1 = 109.6kms−1 and K2 = 252.4kms−1 and the systemic radial velocity V0 =-9.3 kms−1 are obtained, comparable to the data published in the literature. The semi-amplitude of the radial velocity curve of a more massive component K1 and the mass ratio of the components q = 0.412 appeared to be slightly smaller than the values obtained by other authors. An assumption wasmade that a possible reason of this is the presence of hot and/or cold spots on the surface of the components, shifting the effective center of brightness of the visible disk of the component with respect to its center of mass position. It was shown that the AM Leo light curve variations on the time scales of one and more days, registered within the photometric part of the study may be described by the choice of appropriate model of the spot structure.

Astrophysical Bulletin. 2016;71(1):64-74
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Interstellar and circumstellar medium in the direction to IR source IRAS 01005+7910

Sendzikas E.G.

Abstract

Using the high-resolution spectra obtained at the 6-meter telescope of the SAO RAS over 2002–2013, we studied the spectral features of the lines of interstellar medium. The radial velocities of the Na I 5890 Å, Na I 5896 Å, Ca II 3934 Å and Ca II 3968 Å absorption lines were analyzed. Seven diffuse interstellar bands 4964, 5780, 5797, 6196, 6203, 6379 Å were identified in the optical spectrum of IRAS01005+7910. Radial velocities Vr and equivalent widths Wλ of these DIBs were measured, for which the values of the interstellar reddening EB−V and column density of neutral hydrogen log [N(H)] were calculated.

Astrophysical Bulletin. 2016;71(1):75-81
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Photometry and spectroscopy of the luminous red nova PSNJ14021678+5426205 in the galaxy M101

Goranskij V.P., Barsukova E.A., Spiridonova O.I., Valeev A.F., Fatkhullin T.A., Moskvitin A.S., Vozyakova O.V., Cheryasov D.V., Safonov B.S., Zharova A.V., Hancock T.

Abstract

We present the results of the study of a red nova from the observations carried out with the Russian 6-m telescope (BTA) along with other telescopes of SAO RAS and SAI MSU. To investigate the nova progenitor,we used the data from the Digital Sky Survey and amateur photos available on the Internet. In the period between April 1993 and July 2014, the brightness of the progenitor gradually increased by \(2_ \cdot ^m 2\) in the V-band. At the peak of the first outburst in mid-November 2014, the star reached an absolute visual magnitude of \(- 12_ \cdot ^m 75\) but was discovered later, in February 2015, in a repeated outburst at the magnitude of \(- 11_ \cdot ^m 65\). The amplitude of the outburst was minimum among the red novae, only \(5_ \cdot ^m 6\) in V-band. The Hα emission line and the background of a cool supergiant continuum with gradually decreasing surface temperature were observed in the spectra. Such process is typical for red novae, although the object under study showed extreme parameters: maximum luminosity, maximum outburst duration, minimum outburst amplitude, unusual shape of the light curve. This event is interpreted as a massive OB star system components’merging accompanied by formation of a common envelope and then the expansion of this envelope with minimal energy losses.

Astrophysical Bulletin. 2016;71(1):82-94
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Photopolarimetric observations of the sample of polar candidates

Borisov N.V., Gabdeev M.M., Afanasiev V.L.

Abstract

We presented the first polarimetric observations of five cataclysmic variables: MTDra, 1RXSJ184542.4+483134, CRTSCSS081231 J071126+440405, IPHASJ052832.69+283837.6, and CRTSCSS130604 J215427+155714. Observations in the V band have shown that all the objects are highly circularly polarized. All the objects except the last one change the polarization sign during the orbital period. The object 1RXSJ184542.4+483134 was observed in two brightness states in 2011 and 2012. The brightness decrease of the systemwas accompanied by the increase of the amplitude of circular polarization variation.

Astrophysical Bulletin. 2016;71(1):95-100
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Photometric and spectral studies of the eclipsing polar CRTS CSS081231 J071126+440405

Borisov N.V., Gabdeev M.M., Shimansky V.V., Katysheva N.A., Kolbin A.I., Shugarov S.Y., Goranskij V.P.

Abstract

We present the results of the study of the eclipsing polar CRTS CSS081231 J071126+440405. Photometric observations allowed us to refine the orbital period of the system \(P_ \circ = 0_ \cdot ^d 0.08137673\). Considerable changes in the appearance of the object’s spectra have occurred over the period of September 20–21, 2001: the slope of the continuum changed from “red” to “blue”, and the variability of the line profiles over the duration of the orbital period has also changed. Doppler maps have shown a shift of the emission line-forming region along the accretion stream closer to the white dwarf. We measured the duration of the eclipse of the system and imposed constraints on the inclination angle \(78_ \cdot ^ \circ 7 < i < 79_ \cdot ^ \circ 3\). The derived radial velocity amplitude was used to obtain the basic parameters of the system: M1 = 0.86 ± 0.08M, M2 = 0.18 ± 0.02 M, q = 0.21 ± 0.01, RL2 = 0.20 ± 0.03 R, A = 0.80 ± 0.03 R. The spectra of the object exhibit cyclotron harmonics. Their comparison with model spectra allowed us to determine the parameters of the accretion column: B = 31–34 MG, Te = 10–12 keV, θ = 80–90°, and Λ = 105.

Astrophysical Bulletin. 2016;71(1):101-113
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Conceptual approach to astronomical problems

Skvortsov N.A., Avvakumova E.A., Bryukhov D.O., Vovchenko A.E., Vol’nova A.A., Dluzhnevskaya O.B., Kaigorodov P.V., Kalinichenko L.A., Kniazev A.Y., Kovaleva D.A., Malkov O.Y., Pozanenko A.S., Stupnikov S.A.

Abstract

New technical capabilities have brought about the sweeping growth of the amount of data acquired by the astronomers from observations with different instruments in various parts of the electromagnetic spectrum. We consider conceptual approach to be a promising tool to efficiently deal with these data. It uses problem domain knowledge to formulate the tasks and develop problem-solving algorithms and data analysis methods in terms of domain concepts without reference to particular data sources, and thereby allows solving certain problems in general form. We demonstrate the benefits of conceptual approach by using it to solve problems related to search for secondary photometric standard candidates, determination of galaxy redshifts, creation of a binary and multiple star repository based on inhomogeneous databases, and classification of eclipsing binaries.We formulate and solve these problems over specifications of astronomical knowledge units such as photometric systems, astronomical objects, multiple stars, etc., and define them in terms of the corresponding problem domains independently of the existing data resources.

Astrophysical Bulletin. 2016;71(1):114-124
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Cryogenically cooled low-noise amplifier for radio-astronomical observations and centimeter-wave deep-space communications systems

Vdovin V.F., Grachev V.G., Dryagin S.Y., Eliseev A.I., Kamaletdinov R.K., Korotaev D.V., Lesnov I.V., Mansfeld M.A., Pevzner E.L., Perminov V.G., Pilipenko A.M., Sapozhnikov B.D., Saurin V.P.

Abstract

We report a design solution for a highly reliable, low-noise and extremely efficient cryogenically cooled transmit/receive unit for a large antenna system meant for radio-astronomical observations and deep-space communications in the X band. We describe our design solution and the results of a series of laboratory and antenna tests carried out in order to investigate the properties of the cryogenically cooled low-noise amplifier developed. The transmit/receive unit designed for deep-space communications (Mars missions, radio observatories located at Lagrangian point L2, etc.) was used in practice for communication with live satellites including “Radioastron” observatory, which moves in a highly elliptical orbit.

Astrophysical Bulletin. 2016;71(1):125-128
pages 125-128 views