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J/A+AS/130/513      Calcium triplet synthesis (Garcia-Vargas+ 1998)

Calcium triplet synthesis Garcia-Vargas M.L., Molla M., Bressan A. <Astron. Astrophys. Suppl. Ser. 130, 513 (1998)> =1998A&AS..130..513G (SIMBAD/NED BibCode)
ADC_Keywords: Equivalent widths ; Models, evolutionary Keywords: galaxies: stellar content; starbursts; elliptical Abstract: We present theoretical equivalent widths for the sum of the two strongest lines of the calcium triplet, CaT index, in the near-IR (λλ 8542, 8662Å), using evolutionary synthesis techniques and the most recent models and observational data for this feature in individual stars. We compute the CaT index for Single Stellar Populations (instantaneous burst, standard Salpeter-type IMF at four different metallicities, Z=0.004, 0.008, 0.02 (solar) and 0.05, and ranging in age from very young bursts of star formation (few Myr) to old stellar populations, up to 17Gyr, representative of galactic globular clusters, elliptical galaxies and bulges of spirals. The interpretation of the observed equivalent widths of CaT in different stellar systems is discussed. Composite-population models are also computed as a tool to interpret the CaT detections in star-forming regions, in order to disentangle between the component due to Red Supergiant stars, RSG, and the underlying, older, population. CaT is found to be an excellent metallicity-indicator for populations older than 1 Gyr, practically independent of the age. We discuss its application to remove the age-metallicity degeneracy, characteristic of all studies of galaxy evolution based on the usual integrated indices (both broad band colors and narrow band indices). The application of the models computed here to the analysis of a sample of elliptical galaxies will be discussed in a forthcoming paper Gorgas et al. 1997). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table12.dat 41 188 *Synthetic Luminosities table34.dat 41 188 *Synthetic Calcium Triplet Equivalent Widths, according to Jorgensen et al. (1992A&A...254..258J) theoretical calibrations (II). table56.dat 36 188 Synthetic Calcium Triplet Equivalent Widths, according to Diaz et al. (1989MNRAS.239..325D, DTT89) empirical calibrations (I). table7.dat 44 87 Two-Populations composite models according to Jorgensen et al. (1992A&A...254..258J) calibrations. table8.dat 44 120 Three-Populations composite models according to Jorgensen et al. (1992A&A...254..258J) calibrations. table9.dat 44 87 Two-Populations composite models according to Diaz et al. (1989MNRAS.239..325D) calibrations. table10.dat 44 120 Three-Populations composite models according to Diaz et al. (1989MNRAS.239..325D) calibrations. tables.tex 124 814 LaTeX version of the tables tables.ps 72 1090 PostScript version of tables
Note on table12.dat, table34.dat, table56.dat: Standard IMF: α=2.35, mlow=0.8M, mup=100M), MT=1x106M
Byte-by-byte Description of file: table12.dat
Bytes Format Units Label Explanations
1- 5 F5.2 [yr] logAge Cluster age 7- 9 F3.1 Sun Z Metalicity value value relative to the Sun 11- 19 E9.3 solLum LUV Luminosity in the UV (at 2000Å) 21- 29 E9.3 solLum Lopt Luminosity in the optical (at 4850Å), representative of the continuum near Hβ 31- 40 E10.3 solLum LIR Luminosity in the infrared (at 2.17µm, near Brγ)
Byte-by-byte Description of file: table34.dat table56.dat
Bytes Format Units Label Explanations
1- 5 F5.2 [yr] logAge Single Stellar Population (SSP) age 7- 9 F3.1 Sun Z Metallicity value relative to the Sun 11- 19 E9.3 solLum Lcont Continuum luminosity from the SSP (1) 21- 29 E9.3 solLum LCaII Luminosity absorbed in the Ca II lines at 8542 and 8662Å by the stars of the SSP 31- 35 F5.2 0.1nm EW(CaT) Equivalent width of CaT (2)
Note (1): Nebular emission not included, taking an average value in the DTT89's spectral band-pass Note (2): Computed as the ratio between LCAII and the total continuum luminosity, in which both the stellar and the nebular contribution are taken into account (the lines at 8542, 8662 Å)
Byte-by-byte Description of file: table7.dat table8.dat table9.dat table10.dat
Bytes Format Units Label Explanations
1- 6 F6.2 --- Prop ? Proportion of the populations considered (1) 8- 14 F7.1 Myr Age1 Age of the first population (2) 15 A1 --- n_Age1 [+] + when more than one population 16- 20 I5 Myr Age2 ? Age of the second population 21 A1 --- n_Age2 [+] + when more than two populations 22- 26 I5 Myr Age3 ? Age of the third population 29- 31 F3.1 Sun Z Metallicity value relative to the Sun 33- 37 F5.2 0.1nm EW(CaT) Equivalent width of CaT in absorption 39- 43 F5.1 0.1nm EW(Hb) ? Equivalent width of Hbeta in emission (3)
Note (1): P is the ratio of the continuum luminosity at 6500Å (close to Hα) of the young and intermediate population (when present) to the total light. As an example, P=0.10 indicates a model in which the population characteristic of the region (young or young+intermediate) is contributing 10% to the total light in the continuum at Hα. If P is not given, a single population, or a combination of two coexisting young populations contributing 50% in mass each, have been considered. Note (2): Age1=2.5 + Age2=10000 correspond to a model in which a young burst of 2.5Myr is combined with an old population of 10Gyr. Note (3): If this value is missing then the adopted population(s) is (are) too old to produce ionizing photons
Acknowledgements: Maria Luisa Garcia Vargas
(End) Patricia Bauer [CDS] 18-Jun-1998
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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