Toward a Solution for the Ca II Triplet Puzzle: Results from Dwarf Elliptical Galaxies

We present new estimates of ages and metallicities, based on VLT FORS optical (4400-5500 AAA) 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 narrowband photometry...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2007-12, Vol.670 (2), p.L101-L104
Main Authors: Michielsen, Dolf, Koleva, Mina, Prugniel, Philippe, Zeilinger, Werner W, De Rijcke, Sven, Dejonghe, Herwig, Pasquali, Anna, Ferreras, Ignacio, Debattista, Victor P
Format: Article
Language:English
Subjects:
Astronomy
Astrophysics
Earth, ocean, space
Exact sciences and technology
Physics
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Summary:We present new estimates of ages and metallicities, based on VLT FORS optical (4400-5500 AAA) 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 narrowband 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 ( similar to 8500 AAA) 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.
ISSN:1538-4357
0004-637X
2041-8205
1538-4357
2041-8213
DOI:10.1086/524404