New age indicators for stellar populations

We apply the method of principal component analysis to a sample of simple s tellar populations to select some age sensitive spectral indices. Besides t he well-known age sensitive index H beta, we also find some new age sensiti ve indices, G4300 and Fe4383, C(2)4668, and Mgb. In addition, we find that these spectral indices sensitive to age depend on the metallicity of stella r population, H beta and G4300 are more suitable to determine the age of lo w metallicity stellar population, while C24668 and Mgb are more suitable to the high metallicity stellar population.