Satellite absorption lines and the temperature dependence of x-ray absorption features in high-temperature plasmas.

In absorption spectroscopy, absorption features impressed on the spectrum of a continuum background source are interpreted in terms of conditions in an absorbing foreground medium. If the opacity per ion for a particular transition beginning from some initial state is known, then the areal density (i.e., the path integral of the density along the path of the continuum propagation) of ions in that state within the absorbing medium can be inferred from the attenuation of the background continuum due to that t r an~ i t i on . ' ~~ If the relative abundance of ion species can be determined in this way, then temperature can also be inferred from the observed state of ionization, which can be modeled in terms of temperature and density.2