Abstract
A sample of 211 giant stars with spectral types K and M has been analyzed, for which pseudo-equivalent widths were measured and stellar atmospheric parameters were previously identified. The spectra of these stars have been taken from a stellar library observed with the Coudé telescope at the Kitt Peak National Observatory, with a resolution of ∼ r Aand covering a spectral region of λλ 3460-9460 Å set of first and second order polynomials is applied, which involves one, two, or three independent variables and allows us to estimate the precision in the effective temperature T[eff], the surface gravity, logg and the metallicity [Fe/H] in terms of the pseudo-equivalent widths of seven absorption features in the near IR regions λλ 5400-9500 Å. The results obtained from linear fittings with three independent variables to the three fundamental atmospheric parameters attain residual averages of (149Â+/-15), (0.26Â+/-0,02), (0.12Â+/-0.02), while the quadratic fittings attain residual averages of (146Â+/-16), (0.25Â+/-0.02), (0.12Â+/-0.02), respectively. It is observed from both results that using higher order polynomials does not improve the residual averages with respect to those obtained from linear fittings. The procedure performed in this work follows the Stock & Stock method (1999).
