EDP Sciences
Free access
Volume 398, Number 3, February II 2003
Page(s) 949 - 957
Section Galactic structure and dynamics
DOI http://dx.doi.org/10.1051/0004-6361:20021718

A&A 398, 949-957 (2003)
DOI: 10.1051/0004-6361:20021718

New $\vec{UBVRI}$ color distributions in E-type galaxies

II. Central and mean metallicities
T. P. Idiart1, 2, R. Michard3 and J. A. de Freitas Pacheco1

1  Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France
    e-mail: pacheco@obs-nice.fr
2  Instituto de Astronomia, Geofísica e Ciências Atmosféricas Depto. de Astronomia, Universidade de São Paulo, Av. Miguel Stefano, 4200-CEP 04301-904, S. Paulo, SP-Brazil
    e-mail: thais@iagusp.usp.br
3  Observatoire de Paris, LERMA, 77 Av. Denfert-Rochereau, 75015, Paris, France

(Received 17 September 2001/ Accepted 8 November 2002)

Central and mean metallicities are calculated for a sample of 40 early-type galaxies, whose color gradients were reported in a previous paper (Idiart et al.2002). The present color-metallicity calibration was derived from a grid of evolutionary models which fit the color-magnitude sequence of ellipticals in Coma and Virgo clusters. The mean metallicity gradient derived from our data is $(\Delta{\rm [Fe/H]}/\Delta \log r) = -0.26 \pm 0.08$ and the mean sample average metallicity is ${<{\rm [Fe/H]}>} = 0.01 \pm 0.11$ (rmsd). Central and mean metallicities are correlated with the central velocity dispersion, consistent with the interpretation by metallicity variations of the color-magnitude sequence and of color gradients. Age effects are also discussed, in particular concerning the interpretation of the H $\beta$ line strength in those objects.

Key words: galaxies: ellipticals and lenticular, cD -- galaxies: abundances

Offprint request: R. Michard, raymond.michard@obspm.fr

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© ESO 2003