A grid of synthetic spectra and indices Fe5270, Fe5335, Mgb and Mg2 as a function of stellar parameters and [α/Fe]

Abstract

We have computed a grid of synthetic spectra in the wavelength range λλ 4600-5600 Å using revised model atmospheres, for a range of atmospheric parameters and values of [α-elements/Fe] = 0.0 and +0.4. The Lick indices Fe5270, Fe5335, Mgb and Mg2 are measured on the grid spectra for FWHM = 2 to 8.3 Å. Relations between the indices Fe 5270, Fe5335 and Mg2 and the stellar parameters effective temperature Teff, log g, [Fe/H] and [α/Fe], valid in the range 4000 ≤ Teff ≤ 7000 K, are presented. These fitting functions are given for FWHM = 3.5 and 8.3 Å. The indices were also measured for a list of 97 reference stars with well-known stellar parameters observed at ESO and OHP, and these are compared to the computed indices. Finally, a comparison of the indices measured on the observed spectra and those derived from the fitting functions based on synthetic spectra is presented.