ADC/CDS Standard Document for Catalog:/journal_tables/A+AS/130/513/
ADC/CDS Standard Document for Catalog:| 1. Use the ADC Data Viewer Suite to visualize the data. |
|
| 2. Get the data files via anonymous FTP. (See Note.) |
|
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
({lambda}{lambda} 8542, 8662{AA}), 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:
{alpha}=2.35, m_low_=0.8M_{sun}_, m_up_=100M_{sun}_), M_T_=1x10^6^M_{sun}_
--------------------------------------------------------------------------------
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 2000{AA})
21- 29 E9.3 solLum Lopt Luminosity in the optical (at 4850{AA}),
representative of the continuum near H{beta}
31- 40 E10.3 solLum LIR Luminosity in the infrared (at 2.17{mu}m,
near Br_{gamma}_)
--------------------------------------------------------------------------------
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 8662{AA} 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 {AA})
--------------------------------------------------------------------------------
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 H{beta} in emission (3)
--------------------------------------------------------------------------------
Note (1): P is the ratio of the continuum luminosity at 6500{AA} (close to
H{alpha}) 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 H{alpha}.
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 <mgarcia@ll.iac.es>
================================================================================
(End) Patricia Bauer [CDS] 18-Jun-1998