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Structural Parameters of Globular Clusters in the Fornax Cluster
Elson, Rebecca A. W.; Schade, David J.
We present measurements of the structural parameters of 24 globular cluster candidates with 19 < I < 22, ~4' from NGC 1399, the central giant elliptical galaxy in the Fornax cluster (distance modulus ~31). The data were obtained with the Hubble Space Telescope's Wide Field Camera prior to refurbishment. We use a two-dimensional model-fitting…
Nonthermal Pair Models, Reflection, and X-Ray Spectral Variability of Active Galaxies
Done, C.; Grandi, P.; Urry, C. M.
Standard nonthermal electron-positron pair cascades, including the effects of reflection from an accretion disk, can explain reasonably well the mean spectra of low-luminosity, Seyfert-type active galaxies. We test this model using the spectral variability observed by EXOSAT between 0.05 and 10 keV in five active galaxies: NGC 5548, 3C 120, 3C 273…