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008 211028s9999 xx 000 0 eng d
040 _cIIA Library
080 _a042:524.9
100 _aPrabhu, T. P.
245 4 _aThe Central Regions of Sersic-Pastoriza Galaxies
_cT. P. Prabhu
_h[Ph.D Thesis]
260 _aBangalore
_bIndian Institute of Astrophysics
300 _aiv, 134p.
502 _bDoctor of Philosophy
_cIndian Institute of Astrophysics, Bangalore
520 _aApart from the sustained interest in the enhanced forms of activity in the nuclei of galaxies, other classes of phenomena occurring in the central regions of galaxies have also drawn considerable interest. One such aspect of investigations of the central regions of galaxies is the system of 'hot spots' described originally by Morgan. Though some enthusiasm was derived at least once from the speculation that these are the results of a split due to explosive activity in the nucleus, the spectroscopic evidences obtained by the Burbidges and others proved that the hot spots are simply giant HII complexes. Sersio and Pasteurize broadened the definition of this olass of phenomena observed in the central regions of galaxies to include bright amorphous formations ae well. The purpose of the present investigations ia to test whether the objects from the lists of Series and Pasteurize form a homogeneous class, and to derive parameters which assist in understanding their structure and content. We begin with a brier over view of the principle of superposition of quasi-independent subsystems in galaxies in Chapter 1. We will also describe some of the classification schemes describing the central regions of galaxies Following Morgan's operational approach. we show in Chapter 2 that the central regions of galaxies listed by Sersic and Pastoriza are morphologically intermediate between the normal and Seyfert galaxies. We will also compile an additional list similar central formations based on the descriptions published by various authors. The correlation of the occurrence of such 'pronuclear formations' with the morphology of the parent galaxies is also investigated. The techniques o£ observation and of reduction are presented. They include direct and filter photography, and spectroscopy with a narrow as well as a wide slit. The techniques used in obtaining equal intensity contours are also presented. A morphological classification of the central regions of 50 galaxies from the lists of Series and Pastoriza ia proposed in Chapter 4. The classes range from the elliptioal appearance of ‘E’types, through the formations with bright dist1nct hot spots to the irregular pattern of hot spots of low surface brightness. Some correlations with the types of the parent galaxy are also investigated. The surface photometric data is presented in Chapter 5 in terms of the equal intensity contours in the integrated light (~~4000-8700) for 27 galaxies from the finding list. The equivalent luminosity profiles have been presented for all these galaxies. The blue-infrared colour distribution across the nucleus and the 'perinuclear formation' have been presented in Chapter 6 for one galaxy of type E (NGC 210) and for five of class ~(NGC 613, 1097, 136,5, 1808 and 2903). The nucleus appears reddest in all the casts. The perinuclear formations of class ~ possess neutral colour with respect to the main body of the galaxy. The hot spots of formations of class ~ are generally redder than the main body of the galaxy though a few hot spots are distinctly bluer. The perinuclear regions of NGC t808 are the reddest among the galaxies investigated. The nucleus of NGC 290) has been discovered on our infrared photographs. The mean profiles for different classes of formations have also been computed in Chapter 6. and appear similar to each other in all the oases except in the class ~ . The formations of class ~ have a lower luminosity Gradient than the other classes. A small difference noticed in class or could be due to the existence of discrete hot spots.
650 _aAstronomy and Astrophysics Thesaurus
650 _aGalaxies
650 _aPh.D Thesis
650 _aSersic-{astoriza
700 _aM. K. Vainu Bappu
856 _uhttp://prints.iiap.res.in/handle/2248/125
_yClick Here to Access eThesis
942 _cTD
999 _c6716