Abstract

The integrated spectral properties of a stellar system bring information from the mixture of stellar populations within the system. The (B–V) colour is one of the observational properties that can help determine the age and metallicity of stellar populations in a star cluster or even in galaxies. We have derived a series of empirical calibrations of the intrinsic colour, (B–V)₀, as a function of T_eff, [Fe/H] and [µ/Fe]. The stellar parameters of MILES stars have been redetermined homogeneously. The calibrations were obtained individually for distinct spectral types (O-B, A, F-G-K and M), which were then further subdivided into as many as five ranges in [Fe/H]. For the M types only, the stars were divided into dwarfs and giants. (B–V)₀ was measured directly using the MILES fully calibrated stellar spectra (typical error = 0.025 mag). Here, we present just the (B–V)₀ calibrations for F-G-K types that are split into five [Fe/H] ranges. We find that the error in (B–V)₀ varies from 0.014–0.022 mag. The next main goal is to compute (B–V)₀ self-consistently for semi-empirical simple stellar population models based on MILES.