• Three-Color Photometry of Southern QSOs, Radio Galaxies and Normal Galaxies

      Westerlund, B. E.; Wall, J. V.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1968-12)
      Data on the UBV system are presented for 14 quasistellar radio sources, 8 N galaxies,39 radio galaxies and 19 radioquiet galaxies south of +20° declination. Their positions in the two - color diagram show that the integrated colors of the radio galaxies are similar to those of the radioquiet galaxies of the same morphological type. In an absolute radio magnitude - radio index diagram a linear relation exists between M158 and ím158 Boo for radio galaxies of all classes. The QSO:s, however, do not follow this relation, and possible explanations are considered. The brightness and color distributions in the larger galaxies are described in detail. Our results are combined with other data for a discussion of the compositions of these systems. It is suggested that a fairly high amount of reddening occurs in the central regions of several galaxies, as for instance, in NGC 1068 and NGC 1316.
    • Transfer Effects on X-Ray Lines in Optically Thick Celestial Sources

      Felten, J. E.; Rees, M. J.; Adams, T. F.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1972-05-01)
    • Turbulent Hydrodynamic Line-Stretching: The Random-Walk Limit

      Cocke, W. J.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1970)
    • X-Ray Beaming and Mass Transfer in HZ Her

      Strittmatter, P. A.; Scott, J. S.; Whelan, J. A. J.; Wickramasinghe, D. T.; Univ Arizona, Steward Observ (Steward Observatory, The University of Arizona (Tucson, Arizona), 1973)
      The optical and X -ray properties of HZ Her are analyzed within the framework of a model in which the primary is illuminated by X -ray radiation from a degenerate secondary companion. System parameters are derived on the basis of a simplified model and yield a minimum distance to HZ Her of - 5 kpc. It is shown that the X -ray pulses and 35 day on -off characteristics as well as the shape and modulation of the optical light curve can be understood if (i) the primary is illuminated by X -ray emitted in a beam fixed in a rotating neutron star secondary undergoing forced precession and (ii) energy is supplied by mass transfer from primary to secondary resulting in the formation of a disc around the X -ray source which contributes significantly to the total light.