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Detailed surface photometry of the cD galaxies NGC 4839 and NGC 4874 |
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| Authors: | Gamal B Ali Eman A Shaban Magdy Y Amin M A Rassem |
| Institution: | 1. National Research Institute of Astronomy and Geophysics, 11421, Helwan, Cairo, Egypt 2. National Research Center, Giza, Egypt 3. Astronomy Department, Faculty of Science, Cairo University, Cairo, Egypt |
| Abstract: | We present a detailed photometric study of the cD galaxies NGC 4839 and NGC 4874 based on the technique of surface photometry by fitting ellipses to the isophotes of the galaxies in the u, g, r, i, and z bands using Data Release 7 (DR7) of the Sloan Digital Sky Survey (SDSS). The motivation of this paper is to study the properties (e.g. break radius and surface brightness, color gradient, etc.) of the extended envelope of the two cD galaxies. The surface brightness profile in each band is obtained and fitted to the de Vaucouleurs r 1/4 model. A deviation of the observed profile brighter than the fitted r 1/4 model is noticed especially in the outer part of each galaxy. The profiles of ellipticity, position angle, B4 and shifts with respect to the center of each isophote are also obtained. The color index profiles, u-g, g-r, r-i, and i-z are also obtained and no significant color gradients are noticed except in the outer parts of the two galaxies. The integrated magnitude in each band and color indices are obtained and found to be in good agreement with the published ones. |
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