Far Ultraviolet Spectroscopy of (Non-magnetic) Cataclysmic Variables
  HST and FUSE have provided high signal-to-noise, high-resolution spectra of a variety of cataclysmic variables and have allowed a detailed characterization of FUV emission sources in both high and low states. Here, I describe how this has advanced our understanding of non-magnetic CVs and the substantial interpretive challenges still posed by the observations. In the high state, the FUV spectra are dominated by disk emission that is modified by scattering in high and low velocity material located above the disk photosphere. Progress is being made toward reproducing the high-state spectra using kinematic prescriptions of the velocity field and new ionization and radiative transfer codes. In conjunction with hydrodynamical simulations of the outflows, accurate estimates of the mass loss rates and determination of the launching mechanism are likely forthcoming. In quiescence, the FUV spectra reveal contributions from the WD and the disk. Quantitative analyses have lead to solid measurements of the temperatures and abundances of a number of WDs in CVs, and of a determination of the response of the WD to an outburst. Basic challenges exist in terms of understanding the other components of the emission in quiescence, however, and these are needed to better understand the structure of the disk and the physical mechanisms resulting in ongoing accretion in quiescence. 
Knox S. Long (ST ScI)