Active Galactic Nuclei |
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| Authors: | I S Glass |
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| Institution: | (1) South African Astronomical Observatory, Observatory 7935, P.O. Box 9, Cape Town, South Africa |
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| Abstract: | The term Active Galactic Nuclei includes QSOs (Quasi-Stellar Objects), Seyfert galaxies, BL Lac objects and nuclei showing unusual amounts of star formation. South African work has centred on the photometric properties of these objects, both in the optical(UBVRI) and the infrared(JHKL). Photometry has been used to investigate the nature of the relevant emission mechanisms by studying both the colours of the nuclear components and their variations. In particular, it has been demonstrated convincingly that circumnuclear dust shells are present in several Seyfert 1 galaxies at temperatures of around 1500 K.It has also been shown that the variable component in many Seyfert 1 galaxies retains a constant spectral shape independent of its actual flux at a given time. Further, there is evidence that this shape is largely the same in all Seyfert 1 galaxies. Other studies have concentrated on surveys of morphological, spectroscopic and photometric characteristics of certain classes of galaxies such as those found by the IRAS satellite and those listed in the Arp-Madore catalogue of interacting galaxies. |
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| Keywords: | Active Galaxies Seyferts QSOs BL Lac Objects IRAS |
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