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2 results

  • 6 - Galaxy Mapping Attempt at Tartu Observatory

  • Laird A. Thompson, University of Illinois, Urbana-Champaign
  • Book:
    The Discovery of Cosmic Voids
    Published online:
    02 December 2020
    Print publication:
    10 December 2020, pp 117-133

  • Summary

    Jaan Einasto at first investigated the structure of nearby galaxies and helped to deduce that they are dominated by dark matter. Joeveer at first studied the distribution and dynamics of stars in our Milky Way galaxy. In a joint effort in the mid-1970s, they investigated the galaxy distribution using catalogued data and began to see evidence for large-scale inhomogeneities. A careful review of their investigation reveals shortcomings. The Tartu Observatory 1.5-m telescope was built and commissioned in this era, but it was not equipped with a spectrograph capable of detecting galaxy redshifts. The greatest advantage held by the Estonians came from their early knowledge of computer simulations by Shandarin based on the Zeldovich approximation. At IAU Symposium No. 79 organized by the Estonian astronomers, the first open discussion was held of cosmic voids. Also participating in the meeting was Brent Tully, an expert on the structure of the Local supercluster.

  • Revised activity types for Markarian galaxies

  • A. M. Mickaelian, H. V. Abrahamyan, G. S. Harutyunyan, G. M. Paronyan
  • Journal:
    Proceedings of the International Astronomical Union / Volume 9 / Issue S304 / October 2013
    Published online by Cambridge University Press:
    25 July 2014, pp. 41-42
    Print publication:
    October 2013
    • Article
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  • The sample of Markarian galaxies consists of 1515 UV-excess galaxies containing many active galaxies, both AGN and Starburst (SB). Several catalogs of Markarian galaxies have been published; however activity types are based on old spectroscopic data. The SDSS spectroscopy and some other recent spectral observations allow classify or re-classify many of Markarian galaxies, altogether we have retrieved and studied 779 SDSS and 300 other spectra. Out of 779 SDSS spectra, we have classified 533 HII, 31 Composites, 12 LINERs, 4 S2.0, 5 S1.9, 8 S1.8, 5 NLS1.5, 11 S1.5, 8 NLS1.2, 21 S1.2, 4 NLS1, 4 S1.0, 2 QSO, 11 AGN (without an exact class), 52 Em (HII or AGN), 65 Abs, and 3 Stars. On the other hand, the galaxies are being classified depending on the fact in which wavelength range they have been observed and studied. E.g. some Sy2 type galaxies turn to be Sy1 when classified in IR. Many hidden AGN (in X-ray and IR) appear to be normal galaxies in optical range. So for better understanding, IR spectra are necessary as well.