Abstract

White Dwarfs (WDs) represent the evolutionary endpoint for nearly all stars in the universe. Their atmospheres are usually dominated by either hydrogen, helium, or carbon. In astrophysics, WDs are used to determine the age of the universe, to test current stellar evolutionary models, and to constrain the physics of Type Ia supernovae as well as dark energy. Accurate WD masses are needed for all of these applications. In this defense talk, I review the weaknesses of the currently available WD mass determination methods and show that all such deficiencies can be traced to an incomplete understanding of atomic physics at the temperatures and densities found in WD atmospheres (T_e ~1 eV, n_e ~ 1 x 10¹⁷ cm^-3). The White Dwarf Photosphere Experiment (WDPE) at Sandia National Laboratories Z-machine addresses these shortcomings by providing the needed laboratory data to guide theoretical developments directed at solving the mass determination problems for WDs. Furthermore, recent WDPE results have led to additional questions about fundamental physical assumptions that are relevant not only to stellar atmospheres and our experimental platform, but all of plasma physics. I discuss each of these aspects in the context of atomic, plasma, and WD physics.