The mean stellar parameters from IUE and hipparcos data

Abstract

We elaborate an automatic procedure fitting theoretical flux distributions (Kurucz 1996) to observed low resolution stellar spectra. The procedure is based on the least squares optimalization algorithm and enable us to determine the basic stellar parameters, which minimize RMS (Root Mean Square). This efficient method allows us to retrieve simultaneously T eff , log g, [m/H], θ and E(B–V). To check how reduction procedure can influence the results, we use observations reduced by both NEWSIPS and INES packages. We also calibrate our procedure by an analysis of the standard stars studied by Code et al. (1976). Using the IUE/NEWSIPS observations we find stellar parameters slightly overestimated in comparison with the fundamental data given by Code et al., viz., Δ log T eff =0.002, Δθ=0.03, Δ log L/ L ⊙=0.12 and Δ log R/ R ⊙=0.05. We also apply our method for stars located in Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC). We find satisfactory solutions for [m/H] for these metal deficient objects, viz., on average −1.2 dex and −0.6 dex for SMC and LMC stars, respectively. The results presented in this paper indicate that the low dispersion spectra collected by means of small satellites can be used to determine the fundamental stellar parameters even for extragalactic stars.