We present a simple heuristic model for the time-averaged soft X-ray
temperature distribution in the accretion spot on the white dwarf in polars.
The model is based on the analysis of the Chandra LETG spectrum of the
prototype polar AM Her and involves an exponential distribution of the emitting
area vs. blackbody temperature a(T) = a0 exp(-T/T0). With one free parameter
besides the normalization, it is mathematically as simple as the single
blackbody, but is physically more plausible and fits the soft X-ray and
far-ultraviolet spectral fluxes much better. The model yields more reliable
values of the wavelength-integrated flux of the soft X-ray component and the
implied accretion rate than reported previously.Comment: 5 pages, 3 figures, accepted for publication in Astronomy &
Astrophysic