Evolutionary models of white dwarfs with helium cores

We present seven evolutionary tracks for low-mass white dwarfs with helium cores, ranging in mass from 0.179 to 0.414 M.. We generated the pre-white dwarf models from a 1 M. sequence extending up to the tip of its red-giant branch by applying high mass-loss rates at appropriate positions, and me followed their evolution across the Hertzsprung-Russell diagram and down the cooling path. We discuss the internal structures and cooling properties of these new models and compare them with those of recently published models for low-mass white dwarfs which are based on simplified initial configurations. We also demonstrate that our new models seem to remove the apparent discrepancies between the characteristic ages of millisecond pulsars and the cooling ages of their white dwarf companions.