A New Definition for the Ca4227 Feature: Is Calcium Really Underabundant in Early-type Galaxies?
Abstract
We have investigated the abundance of calcium in early-type galaxies by measuring the strength of the Ca I 4227 absorption line in their integrated spectra. The database used is the large sample of early-type galaxy integrated spectra in Caldwell, Rose, & Concannon (2003). We have measured Ca abundances from the Ca I 4227 feature both by using the Lick Ca4227 index and also by defining a new index, Ca4227_r, that avoids the CN4216 molecular band in the continuum on the blueward side of the line. With the new index definition we measure Ca abundances that are systematically ~0.3 dex higher than with the Lick Ca4227 index. The result is that with the new index definition we obtain higher [Ca/Fe] abundances in early-type galaxies which are more consistent with their well known [Mg/Fe] over-abundances. Hence, we suggest that Ca might be slightly enhanced, relative to Fe, in early-type galaxies.
Keywords
Cite
@article{arxiv.astro-ph/0509764,
title = {A New Definition for the Ca4227 Feature: Is Calcium Really Underabundant in Early-type Galaxies?},
author = {L. C. Prochaska and James A. Rose and Ricardo P. Schiavon},
journal= {arXiv preprint arXiv:astro-ph/0509764},
year = {2016}
}
Comments
25 pages, 9 figures