J/ApJS/111/203 Chemo-evolutionary Population Synthesis II. (Vazdekis+ 1997)
A New Chemo-evolutionary Population Synthesis Model for Early-Type Galaxies.
II. Observations and Results
Vazdekis A., Peletier R., Beckman J.E., Casuso E.
<Astrophys. J. Suppl. Ser. 111, 203 (1997)>
=1997ApJS..111..203V 1997ApJS..111..203V (SIMBAD/NED BibCode)
ADC_Keywords: Models, evolutionary ; Abundances
Keywords: galaxies: abundances - galaxies: evolution - galaxies: nuclei -
galaxies: stellar content
Abstract:
We present the results of applying a new chemo-evolutionary stellar
population model, developed in a previous paper, to new high-quality
observational data of the nuclear regions of two representative
elliptical galaxies and the bulge of the Sombrero galaxy. Here we fit
in detail ∼20 absorption lines and six optical and near-infrared
colors, following two approaches: fitting a single-age,
single-metallicity model and fitting our full chemical evolutionary
model. We find that all the iron lines are weaker than the
best-fitting models predict, indicating that the iron abundance is
anomalous and deficient. We also find that the Ca I index at 4227 A is
much lower than predicted by the models. We can obtain good fits for
all the other lines and observed colors with models of old and
metal-rich stellar populations and can show that the observed radial
gradients are due to metallicity decreasing outward. We find that good
fits are obtained both with fully evolutionary models and with
single-age, single-metallicity models. This is due to the fact that in
the evolutionary model more than 80% of the stars form within 1.5 Gyr
after the formation of the galaxies. The fact that slightly better
fits are obtained with evolutionary models indicates that these
galaxies contain a small spread in metallicity.
Objects:
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RA (2000) DE Designation(s)
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10 47.8 +12 35 NGC 3379
12 29.7 +07 59 NGC 4472
12 40.0 -11 37 NGC 4594
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
ngc3379.dat 26 464 Absorption indices vs. radius for NGC 3379
ngc4472.dat 26 412 Absorption indices vs. radius for NGC 4472
ngc4594.dat 26 412 Absorption indices vs. radius for NGC 4594
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Byte-by-byte Description of file: ngc3379.dat ngc4472.dat ngc4594.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Line Line identification
8- 13 F6.1 arcsec Dist Distance to the galactic center at each
side of the center
15- 20 F6.3 --- Index *Index value
22- 26 F5.3 --- e_Index Estimated error in Index
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Note on Index:
Index value in Å except for the CN1, CN2, Mg1, Mg2 and TiO1
bands which are given in 'magnitudes'
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Origin: AAS CD-ROM series, Volume 8, 1997 Lee Brotzman [ADS] 29-Apr-97
References:
Vazdekis et al., Paper I. 1996ApJS..106..307V 1996ApJS..106..307V
(End) Patricia Bauer [CDS] 09-Jul-1997