Absorption line-strength models based on empirical fitting functions

A number of absorption line-strengths are predicted on the basis of the, so-called, empirical fitting functions:

• The 21 line-strengths of the Lick/IDS system computed on the basis of the Worthey et al. 1994 (ApJS,94,687) fitting funct. The lines strengths are given on the Lick/IDS instrumental response. The spectral resolution depend on the wavelength range. A detailed description of this system is given in Worthey & Ottaviani 1997 (ApJS,111,377).
• Warning: to compare these line-strengths with those measured on galaxy spectra, the data should be transformed to the characteristic wavelength-dependent resolution and instrumental response curve of the LICK/IDS system (see Worthey & Ottaviani 1997 (ApJS,111,377)). See Vazdekis 1999 for a discussion on the limitations of this method and for an alternative approach.
• The 4 higher order Balmer lines of Worthey & Ottaviani 1997 (ApJS,111,377), also on the Lick/IDS instrumental system.
• The 4000Å break on the basis of the fitting functions of Gorgas et al 1999 (A & AS,139,29).The system is under flux-calibration response curve. The resolution is irrelevant.
• The near-IR CaII triplet (CaT*) and Paschen (PaT) indices of Cenarro et al. (2001) computed on the basis of fitting functions of Cenarro et al. (2003). The system is under flux-calibration response curve and the resolution is 1.5Å (FWHM).
• The sTiO and MgI indices (around the near-IR CaII triplet region) computed on the basis of fitting functions of Cenarro et al. (2009). The system is under flux-calibration response curve and the resolution is 1.5Å (FWHM).
• The DCO index in the K band computed on the basis of the fitting functions of Mármol-Queraltó et al. (2008)

Line-strengths are computed for all the SSPs described in this Table. However the age ranges (in Gyr) where these predictions are safe (since do not require many extrapolations of the empirical fitting functions employed by the models) are listed below:

The full set of predictions for each IMF type can be obtained from the following files:

Isochrone	Unimodal	Bimodal	Kroupa Universal	Kroupa Revised	Chabrier
Padova+00	link	link	link	link	link
BaSTI	link	link	link	link	link

 

HEADER_ssp_li includes the appropriate header for these files.

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