Accueil > Équipes > Physique des Galaxies > Jean-François Le Borgne > STELIB : a library of stellar spectra for population synthesis

 

STELIB : a library of stellar spectra for population synthesis

Par Jean-Francois Le Borgne - 24/10/2005

 



STELIB

A stellar Library for stellar population synthesis models



The objective of our Stellar Library is to build an homogeneous library of stellar spectra in the visible range (3200 to 9500A), including stars of all spectral types, luminosity classes and metallicity that can be observed from the ground with the current instrumentation. Most of the stars in our sample have already well determined metallicities. The spectral resolution of our Stellar Library is about 3A FWHM. 



Current version : V3.2, spectra corrected for interstellar extinction and radial velocity, 25 April 2003
V3.1, 2000 September 1, not corrected spectra, still available.



Population synthesis models that follow in detail the chemical and spectral evolution of stellar systems are needed in order to interpret observational data on both distant galaxies (blue systems seen early on in their chemical history) and nearby ones (either ellipticals or spiral bulges containing stars of metallicity higher than solar or dwarf blue galaxies which are currently forming stars at metallicities considerably lower than solar). The possibility of building detailed spectro-chemical evolution models of stellar populations using evolutionary synthesis techniques is limited by the inexistence of a comprehensive library of stellar spectra comprising stars in a wide metallicity range, from well below solar ([Fe/H] from
-  2 to -1) to above solar metallicities ([Fe/H]>0). Current evolutionary synthesis models follow the evolution of stars of solar metallicity and in the visible range are largely based on the Gunn and Stryker spectral atlas or Kurucz model stellar atmospheres.
The use of theoretical model atmospheres is quite permissible in evolutionary population synthesis. However, in general, the resulting synthetic spectra do not reproduce the spectral features observed in composite stellar populations with the same degree of accuracy as models based solely on observed stellar spectra. One of the weakest points in using theoretical model atmospheres is the fact that the spectra for the coolest stars in some of the most relevant regions in the HR diagram (giants) are not contained in Kurucz atlas. The Kurucz atlas does not contain model atmospheres for stars cooler than 3500 K and one use of some rudimentary approximations to construct the missing spectra.
The main objective of our Stellar Library is to build a homogeneous library of stellar spectra in the visible range (3200 to 9500A), including stars of all spectral types and luminosity classes that can be observed from the ground with the current instrumentation. Most of the stars in our sample have already well determined metallicities.
It is worth mentioning that the Gunn and Stryker atlas, so useful in this kind of studies, was not compiled as part of a specific observing project, but the spectra were obtained during different circumstances.

The spectral resolution of our Stellar Library is about 3A FWHM, compared to 10 to 20 for Gunn and Stryker atlas.


 

 

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