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J. Rhee (Center for Space Astrophysics), R. M. Rich (UCLA), Y.-J. Sohn, Y.-W Lee (Center for Space Astrophysics & Yonsei Univ.), A. Gil de Paz (Carnegie Observatories & Universidad Complutense de Madrid), J.-M. Deharveng, J. Donas, A. Boselli (Laboratorie d'Astrophysique de Marseille), S.-C Rey (Chungnam Univ.), S. K. Yi (Center for Space Astrophysics & Yonsei Univ.), GALEX Team
We present the results of surface photometry on the far-UV (FUV) and near-UV (NUV) images of 23 nearby elliptical galaxies and spiral bulges taken from the GALEX (Galaxy Evolution Explorer). Surface brightness profiles of most galaxies are consistent with de Vaucouleurs' r1/4 law except for some cases more consistent with exponential profiles. We analyze the radial profiles of UV color, (FUV—NUV), and Mg2 line index to investigate a correlation between the gradients of UV color and metal abundance for early-type galaxies. UV color gradients are calculated by applying least square fitting to UV color profile up to effective radius, while Mg2 line strength gradients are compiled for 12 galaxies from previous works. For the 12 early-type galaxies, we find that UV color profiles have a trend to become bluer inward and there is a weak correlation between the gradients of UV color and Mg2 line strength in the sense that galaxies with larger UV color gradients tend to have stronger metal abundance gradients. We also explore the properties of the GALEX-measured ultraviolet rising flux in 96 nearby elliptical galaxies, as a function Lick Mg2 index and velocity dispersion. We include 36 galaxies in the Virgo cluster from the sample of Boselli et al (2005). We find no correlation between the Mg2 index, and log \sigma and FUV-r. This confirms the findings of Rich et al (2005) for a sample of GALEX/SDSS quiescent early-type galaxies. This is true both for the integrated light, and for nuclear colors. We find a weak correlation between Mg2 and FUV-NUV.
We gratefully acknowledge NASA's support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the Centre National d’Etudes Spatiales of France and the Korean Ministry of Science and Technology.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.