1999/06/07 by T. R. Marsh, T.R. Marsh · 1 citation
Engineering · Physics and Astronomy · #Astronomy and Astrophysical Research #Balmer series #Binary number #Binary star #Black dwarf #Blue dwarf #Brown dwarf #Mass distribution #Orbit (dynamics) #Space Technology and Applications #Stars #Stellar, planetary, and galactic studies #White dwarf #astro-ph
paper · pdf · doi:10.1016/s1387-6473(00)00024-5
6 pages, to appear in proceedings of Warner symposium on Cataclysmic Variable stars
arxiv created 1999/06/07 · openalex publication_date 2000/04/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
I review detached binaries consisting of white dwarfs with either other white dwarfs or low mass main-sequence stars in tight orbits around them. Orbital periods have been measured for 15 white dwarf/white dwarf systems and 22 white dwarf/M dwarf systems. While small compared to the number of periods known for CVs (>300), I argue that each variety of detached system has a space density an order of magnitude higher that of CVs. While theory matches the observed distribution of orbital periods of the white dwarf/white dwarf binaries, it predicts white dwarfs of much lower mass than observed. Amongst both types of binary are clear examples of helium core white dwarfs, as opposed to the usual CO composition; similar systems must exist amongst the CVs. White dwarf/M dwarf binaries suffer from selection effects which diminish the numbers seen at long and short periods. They are useful for the study of irradiation; I discuss evidence to suggest that Balmer emission is broadened by optical depth effects to an extent which limits its usefulness for imaging the secondary stars in CVs.