Collaborative Research: White Dwarfs in Binaries Across the H-R Diagram with the APOGEE-GALEX-Gaia Catalog

More than 95 percent of stars will eventually end up as white dwarfs - the remains of stars that have used up their nuclear fuel and collapsed to a size equivalent to Earth but with a mass comparable to the Sun. Many of these white dwarfs are locked in a cosmic dance with stellar companions, where they orbit around each other and exchange mass. Such close white dwarf binary systems offer an excellent opportunity to study the late stages of stellar evolution. They can also be used as tracers of the dynamics of the Milky Way galaxy, and they are potential sources of gravitational waves. The goal of this project is to collect data on these systems at a wide range of wavelengths to characterize them and investigate fundamental properties, like what they are made of and how much mass they are sharing. This work will also provide several projects for science students at various stages, and the investigators will work with experts in accessibility to create training programs to teach astronomy to blind and visually impaired people. Most white dwarfs inhabit multiple systems, and a large fraction of those are compact enough to exchange mass, changing the structures and subsequent evolution of both stars. The physical mechanisms that mediate these mass exchanges include common envelope evolution, Roche lobe overflow, wind accretion, mass stripping, and stellar mergers. The main goal of this proposal is to further our understanding of mass transfer processes in interacting systems by assembling a unique observational sample of thousands of post mass-transfer binaries. The source sample combines the GALEX and Gaia databases with APOGEE — a high resolution (R=22,500), high signal-to-noise, multi-epoch, infrared (1.51 μm to 1.69 μm), spectroscopic survey of stars across the Milky Way — to build the most exhaustive survey of post-mass transfer binaries, containing systems with main sequence, subgiant, red giant, and red clump companions. The creation of this APOGEE-GALEX-Gaia Catalog and the proposed analysis of the resulting data set will improve our knowledge of the population of post-mass transfer binaries containing a white dwarf, and map the changes in their properties as a function of the evolution of the non-degenerate companion. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.