Kinematic Properties and Stellar Populations of Faint Early-Type Galaxies. II. Line-Strength Measurements of Central Coma Galaxies
Abstract
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-1. The index-σ relations for our sample, including galaxies with σ < 100 km s-1 (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-1 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2009
- DOI:
- 10.1088/0004-637X/691/2/1862
- arXiv:
- arXiv:0810.3237
- Bibcode:
- 2009ApJ...691.1862M
- Keywords:
-
- galaxies: abundances;
- galaxies: clusters: individual: Coma;
- galaxies: dwarf;
- galaxies: elliptical and lenticular;
- cD;
- Astrophysics
- E-Print:
- Accepted For Publication in ApJ, corrected error bars