Absorption due to gas in coronal equilibrium.
An analytic model for calculating absorption spectra from gas which is in coronal equilibrium is available. This model is the coronal analog of the 'warmabs' model. It uses the same xstar atomic database, but uses ionization equilibrium calculated in the absence of a photoionizing flux, assuming a given electron temperature.
Similar to warmabs it has the advantage that it avoids the intrinsic approximations associated with use of tables for absorption with variable abundances treated as multiplicative parameters, and the intrinsic clumsiness of the use of tables. It also allows the use of arbitrary spectral resolution, not limited by the internal xstar spectral resolution. To use it, go to the xstar page and follow the instructions there. Please send reports of bugs and problems to tim-at-xstar.gsfc.nasa.gov.
Keith Arnaud, Lab. for High Energy Astrophysics, NASA/Goddard Space Flight Center
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