Astronomy and Astrophysics – Astronomy
Scientific paper
May 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009rmxac..35r.306s&link_type=abstract
XII Latin American IAU Regional Meeting (Eds. G. Magris, G. Bruzual, & L. Carigi) Revista Mexicana de Astronomía y Astrofísica (
Astronomy and Astrophysics
Astronomy
Scientific paper
We present spectroscopic age and metallicity predictions for a sample of 20 Globular Clusters in the massive E0 galaxy NGC 1407 (data from Cenarro et al. 2007, AJ, 134, 391) and for the Galacic Globular Clusters data from the Library of Integrated Spectra of Galactic Globular Clusters (GGC's) from Schiavon et al. (2005, ApJS, 160, 163) including the widely studied 47 Tuc cluster. Using index-index plots we compared model Single Stellar Populations (SSP's) spectra to the integrated spectra of both samples of Globular Clusters using high resolution line strength indices (Stock, in prep.) and the syntethic SSP's models from P. Coelho (2007, private comm.) as well as the CB07 solar models. For the GC's in NGC1407, the predictions from the syntethic models's with [α /Fe]=0.4 are in good agreement with the results from Cenarro et al. (2007, AJ, 134, 391), taking into account that the dispersion is partially due to the fact that the mean [α/Fe] ratio of the sample is ≈ 0.3 dex, resulting in younger ages and lower metallicities (Thomas et al. 2003, A&A, 401, 429). We observe a bimodal distribution of the Fe4383+ index which is in turn an indicator of metallicity, also seen in Cenarro et al. (2005). The CB07 models predict ages that are widely spread over the plot yielding ages greater than 14 Gyrs. The metallicity derived from these models are very low for almost all the objects (Z < 0.008). The distribution of the GGC's on the syntethic model grid shows a trend in the sense that metal poor clusters are younger than metal rich ones, but this effect might not be real (de Angeli et al. 2005, AJ, 130, 116). For 47 Tuc we estimate an age of ≈ 10 Gyr, and metallicity Z < 0.011 (<[Fe/H]= -0.5) which are both comparable with the values reported in the literature (Carretta et al. 2000; Liu & Chaboyer 2000, ApJ, 544, 818; Schiavon et al. 2002, ApJ, 580, 873; Gratton et al. 2003, A&A, 408, 529).
Calderon P.
Stock Joann M.
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