Kinematic properties and stellar populations of faint early-type galaxies. II. Line-strength measurements of central coma galaxies



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Matkovic, A. and Guzmán, R. and Sánchez Blázquez, P. and Gorgas García, Francisco Javier and Cardiel López, Nicolás and Gruel, N. (2009) Kinematic properties and stellar populations of faint early-type galaxies. II. Line-strength measurements of central coma galaxies. Astrophysical journal, 691 (2). pp. 1862-1878. ISSN 0004-637X

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We present line-strength measurements for 74 early-type galaxies in the core of the Coma cluster reaching down to velocity dispersions, sigma, of 30 km s(-1). The index-sigma relations for our sample, including galaxies with sigma < 100 km s(-1) (low-sigma), 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 similar to 100 km s(-1) and another group with strong linear relations between an index and log s. We find no connection between the behavior of index-sigma relations with either alpha- 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-sigma galaxies including dE/dS0s are on average younger, less metal rich, and have lower [alpha/Fe] in comparison with E/S0s. Our data show that these trends derived for high-sigma galaxies extend down to dE/dS0s. This is a factor of similar to 2 lower in sigma than previously published work. We confirm that the observed anticorrelation between age and metallicity for high-sigma galaxies is consistent with the effects of correlated errors. Low-sigma 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-sigma counterparts.

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Reproduced by permission of the AAS. © 2009. The American Astronomical Society. All rights reserved. We thank J. Cenarro for his help on investigating the spectra for potential problems and for providing the GC data. We are also grateful to Russell Smith for providing the data from the Hectospec Coma cluster survey and double checking our measurements. R. G. gratefully acknowledges University of Yale for the awarded nights at WIYN telescope. P. Sánchez Blázquez acknowledges the support by a Marie Curie Intra-European Fellowship within the 6th European Community Framework Programme. We also thank the anonymous referee whose suggestions have improved this work.

Uncontrolled Keywords:Dwarf elliptic galaxies; Globular-clusters; Velocity dispersion; Fundamental-plane; Different environments; Absorption features; Feature indexes; Fornax cluster; Star-formation; Red-sequence
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
Sciences > Physics > Atmospheric physics
ID Code:28062
Deposited On:26 Jan 2015 16:24
Last Modified:10 Dec 2018 15:05

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