J/MNRAS/387/105 Isochrone database for single- and binary-star SSPs (Li+, 2008)
An isochrone data base and a rapid model for stellar population synthesis.
Li Z., Han Z.
<Mon. Not. R. Astron. Soc., 387, 105-114 (2008)>
=2008MNRAS.387..105L 2008MNRAS.387..105L
ADC_Keywords: Models, evolutionary ; Isochrones
Keywords: galaxies: elliptical and lenticular, cD - galaxies: stellar content
Abstract:
We first presented an isochrone data base that can be widely used for
stellar population synthesis studies and colour-magnitude diagram
(CMD) fitting. The data base consists of the isochrones of both
single-star and binary-star simple stellar populations (ss-SSPs and
bs-SSPs). The ranges for the age and metallicity of populations are
0-15Gyr and 0.0001-0.03, respectively. All data are available for
populations with two widely used initial mass functions (IMFs), that
is, Salpeter IMF and Chabrier IMF. The uncertainty caused by the data
base (about 0.81 per cent) is designed to be smaller than those caused
by the Hurley code and widely used stellar spectra libraries (e.g.
BaSeL 3.1) when it is used for stellar population synthesis. Based on
the isochrone data base, we then built a rapid stellar population
synthesis (RPS) model and calculated the high-resolution (0.03nm)
integrated spectral energy distributions, Lick indices and colour
indices for bs-SSPs and ss-SSPs. In particular, we calculated the
UBVRIJHKLM colours, ugriz colours and some composite colours that
consist of magnitudes on different systems. These colours are useful
for disentangling the well-known stellar age-metallicity degeneracy
according to our previous work. As an example for applying the
isochrone data base for CMD fitting, we fitted the CMDs of two star
clusters (M67 and NGC1868) and obtained their distance moduli, colour
excesses, stellar metallicities and ages. The results showed that the
isochrones of bs-SSPs are closer to those of real star clusters. It
suggests that we should take the effects of binary interactions into
account in stellar population synthesis. We also discussed on the
limitations of the application of the isochrone data base and the
results of the RPS model.
Description:
Following the initial mass functions (IMFs) of Salpeter
(1955ApJ...121..161S 1955ApJ...121..161S ) and Chabrier (2003ApJ...586L.133C 2003ApJ...586L.133C), the
isochrones of both binary-star and single-star stellar populations
(bs-S SPs and ss-SSPs) are calculated. The isochrones are presented
using a statistical method, so that one can get and use the isochrone
data base conveniently. The data base supplies the isochrones for
populations with 7 metallicities (0.0001-0.03) and 151 ages (0-15Gyr).
The evolution of stars are calculated using the code of Hurley
(2002MNRAS.329..897H 2002MNRAS.329..897H), and the default parameters are taken when
evolving binary stars. The data base can be used to quickly model
simple or composite stellar populations, to model the evolution of
galaxies, and to fit the colour-magnitude diagrams of star clusters.
Examples please refer to our paper published on MNRAS
(2008MNRAS.387..105L 2008MNRAS.387..105L).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
salpbsz1.dat 38 627442 Isochrones for bs-SSPs with Salpeter IMF and Z=0.0001
salpbsz2.dat 38 654697 Isochrones for bs-SSPs with Salpeter IMF and Z=0.0003
salpbsz3.dat 38 639859 Isochrones for bs-SSPs with Salpeter IMF and Z=0.001
salpbsz4.dat 38 595848 Isochrones for bs-SSPs with Salpeter IMF and Z=0.004
salpbsz5.dat 38 592829 Isochrones for bs-SSPs with Salpeter IMF and Z=0.01
salpbsz6.dat 38 534036 Isochrones for bs-SSPs with Salpeter IMF and Z=0.02
salpbsz7.dat 38 521653 Isochrones for bs-SSPs with Salpeter IMF and Z=0.03
chabbsz1.dat 38 589788 Isochrones for bs-SSPs with Chabrier IMF and Z=0.0001
chabbsz2.dat 38 617709 Isochrones for bs-SSPs with Chabrier IMF and Z=0.0003
chabbsz3.dat 38 603739 Isochrones for bs-SSPs with Chabrier IMF and Z=0.001
chabbsz4.dat 38 562989 Isochrones for bs-SSPs with Chabrier IMF and Z=0.004
chabbsz5.dat 38 556543 Isochrones for bs-SSPs with Chabrier IMF and Z=0.01
chabbsz6.dat 38 499604 Isochrones for bs-SSPs with Chabrier IMF and Z=0.02
chabbsz7.dat 38 489123 Isochrones for bs-SSPs with Chabrier IMF and Z=0.03
salpssz1.dat 38 159378 Isochrones for ss-SSPs with Salpeter IMF and Z=0.0001
salpssz2.dat 38 149133 Isochrones for ss-SSPs with Salpeter IMF and Z=0.0003
salpssz3.dat 38 139913 Isochrones for ss-SSPs with Salpeter IMF and Z=0.001
salpssz4.dat 38 129027 Isochrones for ss-SSPs with Salpeter IMF and Z=0.004
salpssz5.dat 38 127244 Isochrones for ss-SSPs with Salpeter IMF and Z=0.01
salpssz6.dat 38 121369 Isochrones for ss-SSPs with Salpeter IMF and Z=0.02
salpssz7.dat 38 117431 Isochrones for ss-SSPs with Salpeter IMF and Z=0.03
chabssz1.dat 38 137729 Isochrones for ss-SSPs with Chabrier IMF and Z=0.0001
chabssz2.dat 38 128486 Isochrones for ss-SSPs with Chabrier IMF and Z=0.0003
chabssz3.dat 38 121116 Isochrones for ss-SSPs with Chabrier IMF and Z=0.001
chabssz4.dat 38 110742 Isochrones for ss-SSPs with Chabrier IMF and Z=0.004
chabssz5.dat 38 108657 Isochrones for ss-SSPs with Chabrier IMF and Z=0.01
chabssz6.dat 38 103017 Isochrones for ss-SSPs with Chabrier IMF and Z=0.02
chabssz7.dat 38 99430 Isochrones for ss-SSPs with Chabrier IMF and Z=0.03
summary.dat 35 4228 Summary of available isochrones
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See also:
VI/96 : Evolutionary Sequences (Fagotto+ 1993-96)
J/A+AS/106/275 : Theoretical isochrones (Bertelli+ 1994)
J/A+AS/141/371 : Low-mass stars evolution tracks + isochrones (Girardi+, 2000)
J/A+A/361/1023 : Evolution models for α-enhanced stars (Salasnich+ 2000)
VI/102 : Geneva stellar evolution tracks and isochrones (Lejeune, 2001)
VI/113 : Evolutionary models of Population II stars (Cariulo+, 2004)
Byte-by-byte Description of files: salp*.dat chab*.dat
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Bytes Format Units Label Explanations
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1- 4 F4.1 Gyr Age [0,15] Age of stellar population
5- 11 F7.0 K Teff [2000,60020] Effective temperature of stars
12- 17 F6.2 [cm/s2] log(g) [-1.5,6] Logarithmic acceleration of gravity
18- 27 F10.5 [solLum] log(L) Logarithmic luminosity (in L☉) of stars
28- 37 F10.5 --- Fraction 1000 times of the fraction of stars (1)
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Note (1):
The value represents 1000 times the fraction of stars located in a
(log(g),Teff) subgrid; one can use Fraction*4000 to get the number
of stars in each sub-grid (the total population is initially 400,000
stars or 200,000 binaries).
The (log(g),Teff) plane is divided into 1089x701 sub-grids, taking
intervals of 0.01 in log(g) (range of -1.5 to 6) and 40K in Teff
(range of -1.5 to 6). The values of Teff and log(g) in the tables
represent the median values of Teff and log(g) of stars in each
sub-grid.
The surface area of each star can be calculated using Teff and
log(L/Lsun). More results can be found at
http://www.ynao.ac.cn/~bps/zhongmu/download.htm.
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Byte-by-byte Description of file: summary.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- IMF Type of IMF: salp (Salpeter) or chab (Chabrier)
6- 7 A2 --- SP Stellar population: ss (single-star)
or bs (binary-star)
9- 14 F6.4 --- Z Metallicity (1)
16 I1 --- iz [1,7] Index of metallicity (1)
18- 21 F4.1 Gyr Age Age of the isochrone
23- 28 I6 --- Rec1 First line in file dealing with the isochrone (2)
29 A1 --- --- [-]
30- 35 I6 --- Rec2 Last line in file dealing with the isochrone (2)
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Note (1): 7 metallicities are available:
0.0001, 0.0003, 0.001, 0.004, 0.01, 0.02, 0.03
Note (2): the corresponding file name is the concatenation of:
IMF SP "z" iz ".dat"
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Acknowledgements:
Zhongmu Li, zhongmu.li(at)gmail.com
(End) Patricia Vannier [CDS] 23-Jun-2008