Poster abstract details

Radial abundance gradients are extremely important constraints for evolution models of the Milky Way and other galaxies. They can be obtained by combining data from young objects (HII regions, OB stars), with the corresponding data from older objects (open clusters, planetary nebulae). There is presently some controversy regarding both the magnitude and the time evolution of the gradients, and progress in the area depends critically on the age determinations of these objects. We have developed several methods to estimate the ages of planetary nebula central stars (CSPN). In this work we discuss the effects on the time variation of the gradients resulting from our new determinations of kinematic ages of CSPN. The main conclusion is that most objects in the PN sample with accurate radial velocities have ages under 3 Gyr approximately. This affects the time evolution of the gradients, in the sense that the expected differences between the gradients of older and younger objects are smaller than usually assumed. (FAPESP/CNPq).