相关论文: Ages and Metallicities in Elliptical Galaxies from…
The line strength indices Hb, Mg2, and <Fe>, together with their gradients and dependence on the galaxy luminosity (mass), observed in elliptical galaxies are customarily considered as reliable indicators of systematic differences in age…
Using current models of spectrophotometric properties of single age, single metallicity stellar populations I have computed the Mg2, Hbeta, Fe52 and Fe53 line strengths for stellar populations with a metallicity spread. The comparison of…
We investigate the Mg-sigma and <Fe>-sigma relations in a sample of 72 early-type galaxies drawn mostly from cluster and group environments using a homogeneous data-set which is well-calibrated onto the Lick/IDS system. The small intrinsic…
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 address the question whether age and metallicity effects can be disentangled with the aid of the broad-band colours and spectral indices from absorption feature strengths, so that the age of elliptical galaxies can be…
Preliminary results based on a large compilation of line-strength profiles are presented and discussed. Elliptical galaxies (Es) with strong central Mg$_2$ show steeper line-strength gradients. These galaxies are more massive and have…
We revisit the problem of the flat slope of the Mg2 versus <Fe> relationship found for nuclei of elliptical galaxies (Faber et al. 1992; Worthey et al. 1992; Carollo et al. 1993; Davies et al. 1993), indicating that the Mg/Fe ratio should…
The dependences of the velocity ellipsoids of F-G stars of the thin disk of the Galaxy on their ages and metallicities are analyzed based on the new version of the Geneva-Copenhagen Catalog. The age dependences of the major, middle, and…
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 complement our study of alpha/Fe enhanced stellar population models of Lick absorption indices (Thomas et al. 2003) by comparing two sets of alpha/Fe enhanced models. In both models the impact on Lick indices due to alpha/Fe enhancement…
There are strong indications from recent papers (e.g. Worthey et al. 1992) that the abundance ratio of Mg/Fe, and consequently also O/Fe in giant elliptical galaxies is not solar. The line strengths of two Fe lines at 5270 and 5335 A are…
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…
The gradients in line strength indices such as Mg2 and <Fe> (Carollo & Danziger 1994a,b; Carollo et al. 1993), and their increase toward massive system (Worthey et al. 1992, Faber et al. 1992, Davies et al. 1993, Weiss et al. 1995) observed…
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…
In a sample of elliptical galaxies that span a large range of mass, a previously unused Ca index, CaHK, shows that [Ca/Fe] and [Ca/Mg] systematically decrease with increasing elliptical galaxy mass. Metallicity mixtures, age effects,…
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…
We analyse luminosity-weighted ages and metallicity (Z) of galaxies in a continuous range of environments, i.e. clusters, filaments and voids prevalent in the Coma supercluster ($\sim 100 h^{-1}$ Mpc). Specifically, we employ two absorption…
We have re-studied line-strength gradients of 80 elliptical galaxies. Typical metallicity gradients are d[Fe/H]/dlogr = -0.3. The metallicity gradients do not correlate with any physical properties of galaxies, including central and mean…
The alpha element to iron peak element ratio, for example [Mg/Fe], is a commonly applied indicator of the galaxy star formation timescale (SFT) since the two groups of elements are mainly produced by different types of supernovae that…