Towards a Solution for the Ca II Triplet Puzzle : Results from Dwarf Elliptical Galaxies
Abstract
We present new estimates of ages and metallicities, based on FORS/VLT optical (4400-5500A) spectroscopy, of 16 dwarf elliptical galaxies (dE's) in the Fornax Cluster and in Southern Groups. These dE's are more metal-rich and younger than previous estimates based on narrow-band photometry and low-resolution spectroscopy. For our sample we find a mean metallicity [Z/H] = -0.33 dex and mean age 3.5 Gyr, consistent with similar samples of dE's in other environments (Local Group, Virgo). Three dE's in our sample show emission lines and very young ages. This suggests that some dE's formed stars until a very recent epoch and were self-enriched by a long star formation history. Previous observations of large near-infrared (~8500A) Ca II absorption strengths in these dE's are in good agreement with the new metallicity estimates, solving part of the so-called Calcium puzzle.
Cite
@article{arxiv.0710.4123,
title = {Towards a Solution for the Ca II Triplet Puzzle : Results from Dwarf Elliptical Galaxies},
author = {Dolf Michielsen and Mina Koleva and Philippe Prugniel and Werner W. Zeilinger and Sven De Rijcke and Herwig Dejonghe and Anna Pasquali and Ignacio Ferreras and Victor P. Debattista},
journal= {arXiv preprint arXiv:0710.4123},
year = {2009}
}
Comments
ApJ Letters accepted, 5 pages emulateapj, 2 figures