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J/A+A/534/A9  Synthetic spectra of galactic globular clusters  (Sbordone+, 2011)

Photometric signatures of multiple stellar populations in Galactic globular clusters. Sbordone L., Salaris M., Weiss A., Cassisi S. <Astron. Astrophys. 534, A9 (2011)> =2011A&A...534A...9S
ADC_Keywords: Models, evolutionary ; Spectroscopy ; Clusters, globular Keywords: stars: abundances - Hertzsprung-Russell and C-M diagrams - evolution - globular clusters: general Abstract: We calculated synthetic spectra for typical chemical element mixtures (i.e., a standard alpha-enhanced distribution, and distributions displaying CN and ONa anticorrelations) found in the various subpopulations harboured by individual Galactic globular clusters. From the spectra we determined bolometric corrections to the standard Johnson-Cousins and Stroemgren filters and finally predicted colours. These bolometric corrections and colour-transformations, coupled to our theoretical isochrones with the appropriate chemical composition, provided us with a complete and self-consistent set of theoretical predictions for the effect of abundance variations on the observed cluster colour-magnitude diagrams. Description: We considered a reference isochrone from the BaSTI database ( (Pietrinferni et al. 2006ApJ...642..797P), with the following characteristics: an age of 12Gyr, helium mass fraction Y=0.246 and metal mass fraction Z=0.001, which results in an iron abundance of [Fe/H]=-1.62 for the alpha-enhanced metal mixture of the BaSTI models ([alpha/Fe]∼0.4). Such an isochrone is representative for the first generation population in a typical Galactic GC. Three metal mixtures are considered. The alpha-enhanced mixture employed in the BaSTI database (Pietrinferni et al. 2006ApJ...642..797P), which corresponds to typical first-generation subpopulations in Galactic GCs, is labelled as 'reference'. The first mixture representative of second-generation stars is labelled 'CNONa1', and displays - compared to the reference alpha-enhanced mixture - enhancements of N and Na by 1.8dex and 0.8dex by mass, respectively, together with depletions of C and O by 0.6dex and 0.8dex, respectively. This is the same metal distribution already used in the calculations by Salaris et al. (2006ApJ...645.1131S) and Pietrinferni et al. (2009ApJ...697..275P). An alternative composition for second-generation stars is labelled 'CNONa2'; it is the same as the CNONa1 mixture but for the enhancement of N that in this case is equal to 1.44dex by mass. The important difference between CNONa1 and CNONa2 'second-generation' mixtures is that in the first case, at fixed Fe abundance, the C+N+O mass fraction is enhanced by a factor of 2 compared to the reference composition, whereas the CNONa2 mixture has the same CNO content (in both number and mass fractions) as the reference composition, within 0.5%. ************************************************************************** * * * The synthetic fluxes (FITS files) will be available later * * * ************************************************************************** File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file tablea1.dat 101 99 Abundances for all elements in the considered mixtures
Byte-by-byte Description of file: tablea1.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Z Atomic number 4- 5 A2 --- El Element 7- 16 E10.5 --- fMass Reference fractional mass for Y=0.246 (Z=9.9937e-04) 18- 23 F6.3 --- [El] Reference abundance of element (logN(El)-logN(H)+12)) for Y=0.246 25- 34 E10.5 --- fMass1 Fractional mass for CNONa1, Y=0.246 (Z=1.8343e-03) 36- 41 F6.3 --- [El]1 Abundance of element (logN(El)-logN(H)+12) for CNONa1, Y=0.246 43- 49 F7.4 --- [El]1-[El] Difference between this mixture [El] and reference mixture [El] for CNONa1, Y=0.246 51- 60 E10.5 --- fMass2 Fractional mass for CNONa1, Y=0.400 (Z=1.4597e-03) 62- 67 F6.3 --- [El]2 Abundance of element (logN(El)-logN(H)+12) for CNONaI, Y=0.400 69- 75 F7.4 --- [El]2-[El] Difference between this mixture [El] and reference mixture [El] for CNONa1, Y=0.400 77- 86 E10.5 --- fMass3 Fractional mass for CNONa2, Y=0.246 (Z=9.9937e-04) 88- 93 F6.3 --- [El]3 Abundance of element (logN(El)-logN(H)+12) for CNONa2, Y=0.246 95-101 F7.4 --- [El]3-[El] Difference between this mixture [El] and reference mixture [El] for CNONa2, Y=0.246
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 19-Sep-2011
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