White Dwarfs in the Galactic Plane: The Clustered and Dispersed Population

Abstract

White dwarfs in the densest parts of the Galactic plane have been traditionally overlooked. The reason being a lack of deep optical surveys and the high stellar density, which make it difficult to identify faint stellar objects. We test the potential offered by the new homogeneous optical photometry from the VLT Survey Telescope (VST) Photometric Hα Survey of the Galactic Plane and Bulge (VPHAS+) to white dwarf searches. We have spectroscopically confirmed 17 candidate white dwarfs towards open clusters, for which we determine physical parameters. We suggest six of them to be cluster members, for which we estimate the progenitor masses from stellar evolutionary tracks. We compare our results with relationships between progenitor and white dwarf masses available in the literature. Our pilot study shows that larger samples of white dwarfs in open clusters can be found, providing the sought improvement for the empirical testing of stellar evolutionary theories.