Stars as Laboratories for Fundamental Physics - MPP Theory Group

588 Appendix C
C.3 Bremsstrahlung
Bremsstrahlung dominates for low temperatures and high densities
where electrons are degenerate and the nuclei are strongly correlated.
In a series of papers the emission rate was calculated by Itoh and Kohyama
(1983), Itoh et al. (1984a,b), and Munakata, Kohyama, and Itoh
(1987).
For simple estimates one may use the approximate rate given in
Eq. (11.40). In Fig. C.3 I display the error of this approximation for
iron relative to the results of Itoh and Kohyama (1983). For orientation
the contours of Fig. C.1 for iron are also shown, but only the bremsstrahlung
rates are compared. The simple approximation is not a bad
fit in the regions where bremsstrahlung could be of interest. For carbon
the fit is almost as good, but it is substantially worse for helium.
Fig. C.3. Relative deviation between the bremsstrahlung rates of Itoh and
Kohyama (1983) for iron and the simple approximation formula Eq. (11.40).
The contours where different processes dominate are for iron.