The Fe XXII I (11.92 (Angstrom))/I(11.77 (Angstrom)) Density Diagnostic

Using the Livermore X-ray Spectral Synthesizer, which calculates spectral models of highly charged ions based on HULLAC atomic data, they investigate the temperature, density, and photoexcitation dependence of the I(11.92 {angstrom})/I(11.77 {angstrom}) line ratios of Fe XXII. Applied to the Chandra HETG spectrum of the intermediate polar EX Hya, they find that the electron density of its T{sub e} {approx} 12 MK plasma is log n{sub e} cm{sup -3} - 14.3{sub -0.5}{sup +0.7}, orders of magnitude greater than that observed in the Sun or other late-type stars.