Observations of hot DA white dwarfs

Observations of the hottest white dwarfs offer the opportunity to study the earliest stages of degenerate evolution. For those white dwarfs having pure or nearly pure hydrogen photospheres it is now possible with the current generation of high gravity model atmospheres to achieve substantial refinements in the estimation of atmospheric parameters, such as effective temperature, gravity and trace elements abundance. Such improvements can in turn lead to a clearer picture of DA cooling, have a significant impact on the interpretation of a growing number of soft X-ray observations of hot DAs, and contribute to the understanding of He and trace metal abundance patterns in hot DAs.