294 research outputs found

    Properties of dwarf stars in Cygnus OB2

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    We present the results of investigation of five stars, originally classified as dwarfs, belonging to Cyg OB2 association, their stellar and wind properties. Using both TLUSTY and CMFGEN codes we derived effective temperatures, surface gravities, chemical abundances, mass-loss rates and projected rotation velocities. Due to the fact that distance to the stars is well known, we were able to estimate their luminosities. Using evolutionary models we estimated the ages of these sample stars and find that lower mass ones - MT282 and MT343 - belong to older population of the association. Their ages are greater than 10 Myr. The ages of three other stars - MT317, MT299, MT259 - are between 4-6 Myr.Comment: 16 pages, 10 figures, accepted for publication in PAS

    The problem of turnover of the psychoactive substance al-cohol: abuse, consequences, countermeasures

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    The authors made a review of statistical data on the turnover of the psychoactive substance alcohol within the Russian Federation, Ukraine, United States, Moldova, Hungary, Czech Republic, and England. The authors studied the facts of negative consequences caused by the abuse of the psychoactive substance alcohol and dy-namics of alcohol dependence to develop the measures of resistence to the spread of alcoholism among the population. It was revealed that the WHO records only the quantitative indicators of abuse of alcohol. However, it is necessary to consider the qualitative indicators as well (strong or light alcoholic beverages)yesБелгородский госуниверсите

    Spectral monitoring of AGNs: Preliminary results for Ark 564 and Arp 102B

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    We present preliminary results of the long term spectral monitoring of two active galactic nuclei with different broad line shapes: Ark 564 and Arp 102B. Ark 564 is a bright nearby narrow line Syfert 1 (NLS1) galaxy with relatively narrow permitted optical emission lines and a high FeII/Hβ{\beta} ratio, while Arp 102B is a nearby broad-line radio galaxy with broad double-peaked Balmer emission lines. The spectra of Ark 564 were observed during 11-year period (1999-2009) and the spectra of Arp 102B in the 12-year period (1998-2009), with SAO 6-m and 1-m telescopes (Russia) and the GHAO 2.1-m telescope (Cananea, Mexico).Comment: Presented on "8th Serbian Conference on Spectral Line Shapes in Astrophysics". In revised version minor changes in the tex

    Spectral optical monitoring of 3C390.3 in 1995-2007: I. Light curves and flux variation of the continuum and broad lines

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    Here we present the results of the long-term (1995-2007) spectral monitoring of the broad line radio galaxy \object{3C~390.3}, a well known AGN with the double peaked broad emission lines, usually assumed to be emitted from an accretion disk. To explore dimensions and structure of the BLR, we analyze the light curves of the broad Hα\alpha and Hβ\beta line fluxes and the continuum flux. In order to find changes in the BLR, we analyze the Hα\alpha and Hβ\beta line profiles, as well as the change in the line profiles during the monitoring period. First we try to find a periodicity in the continuum and Hβ\beta light curves, finding that there is a good chance for quasi-periodical oscillations. Using the line shapes and their characteristics (as e.g. peaks separation and their intensity ratio, or FWHM) of broad Hβ\beta and Hα\alpha lines, we discuss the structure of the BLR. Also, we cross-correlate the continuum flux with Hβ\beta and Hα\alpha lines to find dimensions of the BLR. We found that during the monitoring period the broad emission component of the Hα\alpha and Hβ\beta lines, and the continuum flux varied by a factor of \approx 4-5. Also, we detected different structure in the line profiles of Hα\alpha and Hβ\beta. It seems that an additional central component is present and superposed to the disk emission. In the period of high activity (after 2002), Hβ\beta became broader than Hα\alpha and red wing of Hβ\beta was higher than the one of Hα\alpha. We found time lags of \sim95 days between the continuum and Hβ\beta flux, and about 120 days between the continuum and Hα\alpha flux. Variation in the line profiles, as well as correlation between the line and continuum flux during the monitoring period is in the favor of the disk origin of the broad lines with the possible contribution of some additional region and/or some kind of perturbation in the disk.Comment: 32 pages, accepted to A&A, typos correcte
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