Astrophys. J., 691, 1862-1878 (2009/February-1)
Kinematic properties and stellar populations of faint early-type galaxies. II. Line-strength measurements of central Coma galaxies.
MATKOVIC A., GUZMAN R., SANCHEZ-BLAZQUEZ P., GORGAS J., CARDIEL N. and GRUEL N.
Abstract (from CDS):
We present line-strength measurements for 74 early-type galaxies in the core of the Coma cluster reaching down to velocity dispersions, σ, of 30 km/s. The index-σ relations for our sample, including galaxies with σ < 100 km/s (low-σ), differ in shape depending on which index is used. We note two types of relations for the metallic indices: one showing a break in the slope around ∼100 km/s and another group with strong linear relations between an index and log σ. We find no connection between the behavior of index-σ relations with either α- or Fe-peak elements. However, we find indications that the relations are tighter for indices which do not depend on the microturbulent velocities of stellar atmospheres. We confirm previous results that low-σ galaxies including dE/dS0s are on average younger, less metal rich, and have lower [α/Fe] in comparison with E/S0s. Our data show that these trends derived for high-σ galaxies extend down to dE/dS0s. This is a factor of ∼2 lower in σ than previously published work. We confirm that the observed anticorrelation between age and metallicity for high-σ galaxies is consistent with the effects of correlated errors. Low-σ galaxies also show a similar relation between age and metallicity as a result of correlated errors. However, they are offset from this relationship so that, on average, they are less metal rich and younger than their high-σ counterparts.
galaxies: abundances - galaxies: clusters: individual: Coma - galaxies: dwarf - galaxies: elliptical and lenticular, cD
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<Available at CDS (J/ApJ/691/1862): table1.dat table2.dat>
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