Abstract
A number of empirical correlations that allow us to calculate the effective temperature and surface gravity for a set of evolved post-AGB and RV Tauri stars are determined using as calibrators the intrinsic colors of 2MASS (Two Micron All Sky Survey) photometry. We have analyzed a total sample of 36 stars of which 25 are post-AGB stars and 11 are RV Tauri stars, respectively. A group of 11 stars with parallax measures were used as calibrators of the absolute magnitude. The result for T_eff and log g from intrinsic colors (J - H)_0 and (H-K_s)_0 at the near-infrared pass bands reach a dispersion of 220 K and 0.2, respectively. We can estimate the absolute magnitude using the intrinsic color in the near-infrared band with an uncertainty of 0.28 mag. This indicates that (J - H)_0 and (H - K_s)_0 show sensitivity to the absolute magnitude.
