Related papers: Probing the Age of Elliptical Galaxies
Systematic variations in the line strength indices H_beta, Mg2, and <Fe> are observed across elliptical galaxies and from one object to another. Furthermore arguments are given for an enhancement of Mg (\alfa in general) with respect to Fe…
The mean ages of early-type galaxies obtained from the analysis of optical spectra, give a mean age of 8 Gyr at z = 0, with 40% being younger than 6 Gyr. Independent age determinations are possible by using infrared spectra (5-21 microns),…
Using new narrowband color observations of early-type galaxies in clusters, we reconstruct the color-magnitude relation (CMR) with a higher degree of accuracy than previous work. We then use the spectroscopically determined ages and…
We have compiled a sample of 2728 nearby ($z<0.08$) elliptical galaxies with photometry in the $g,r,i,z$ bands from the Sloan Digital Sky Survey (SDSS) and $J,H,K$ photometry from the Two Micron All Sky Survey (2MASS). Stellar masses,…
New calibrations of spectrophotometric indices of elliptical galaxies as functions of spectrophotometric indices are presented, permitting estimates of mean stellar population ages and metallicities. These calibrations are based on…
The origin of color gradients in elliptical galaxies is examined by comparing model gradients with those observed in the Hubble Deep Field. The models are constructed so as to reproduce color gradients in local elliptical galaxies either by…
Spectroscopic studies of elliptical galaxies show that their stellar population ages, mean metallicity, and $\alpha$-enhancement traced by [Mg/Fe] all increase with galaxy stellar mass or velocity dispersion. We use one-zone galactic…
We have assembled a catalogue of relative ages, metallicities and abundance ratios for about 150 local galaxies in field, group and cluster environments. The galaxies span morphological types from cD and ellipticals, to late type spirals.…
In this paper we investigate the relation between the detailed isophotal shape of elliptical galaxies and the strength of the H beta absorption in their spectra. We find that disky galaxies have higher H beta indices. Stellar population…
In this study we present a simple model of elliptical galaxies aimed at interpreting the gradients in colours and narrow band indices observed across these systems. Salient features of the model are the gradients in mass density and star…
In this paper we present new chemo-spectro-photometric models of elliptical galaxies in which infall of primordial gas is allowed to occur. They aim to simulate the collapse of a galaxy made of two components, i.e. luminous material and…
In this paper, basic observational properties of elliptical galaxies such as the integrated spectra, the chemical abundances and the enhancement of $\alpha$-elements inferred from broad-band colors and line strength indices $Mg_2$ and $< Fe…
The correlation between [Mg/Fe] and galaxy mass found in elliptical galaxies sets a strong constraint on the duration of star formation. Furthermore, the colour-magnitude relation restricts the range of ages and metallicities of the stellar…
We probe the stellar population age and metallicity distributions in nearby elliptical galaxies over the largest extension to date. Long-slit spectroscopy is made by using the spectrograph SCORPIO of the 6-m telescope of the Special…
In models of galaxy formation in a hierarchical Universe, elliptical galaxies form through the merging of smaller disk systems. These models yield a number of testable predictions if reliable techniques for determining the relative ages and…
The mid-infrared (10-20 um) luminosity of elliptical galaxies is dominated by the integrated emission from circumstellar dust in red giant stars. As a single stellar population evolves, the rate of dusty mass loss from red giant stars…
We derive new spectral H_gamma index definitions which are robust age indicators for old and relatively old stellar populations and thus have great potential for solving the age-metallicity degeneracy of galaxy spectra. To study H_gamma as…
Evolutionary models of elliptical galaxies are constructed by using a new population synthesis code. Model parameters are calibrated to reproduce the observed colour-magnitude (CM) relation of Coma ellipticals in $V-K$ vs. $M_{V}$ diagram.…
The tightness of the observed colour-magnitude and Mg$_{2}$- velocity dispersion relations for elliptical galaxies has often been cited as an argument against a picture in which ellipticals form by the merging of spiral disks. A common view…
Various methods for age dating globular clusters in ellipticals are presented. We first present spectroscopy of individual globular clusters (feasible with the advent of the 10m-class telescopes), and the measurement of Balmer line indices.…