CHIANTI—An Atomic Database for Emission Lines. VI. Proton Rates and Other Improvements

The CHIANTI atomic database contains atomic energy levels, wavelengths,radiative transition probabilities and electron excitation data for a largenumber of ions of astrophysical interest. Version 4 has been released, andproton excitation data is now included, principally for ground configurationlevels that are close in energy. The fitting procedure for excitation data,both electrons and protons, has been extended to allow 9 point spline fits inaddition to the previous 5 point spline fits. This allows higher quality fitsto data from close-coupling calculations where resonances can lead tosignificant structure in the Maxwellian-averaged collision strengths. Theeffects of photoexcitation and stimulated emission by a blackbody radiationfield in a spherical geometry on the level balance equations of the CHIANTIions can now be studied following modifications to the CHIANTI software. Withthe addition of H I, He I and N I, the first neutral species have been added toCHIANTI. Many updates to existing ion data-sets are described, while severalnew ions have been added to the database, including Ar IV, Fe VI and Ni XXI.The two-photon continuum is now included in the spectral synthesis routines,and a new code for calculating the relativistic free-free continuum has beenadded. The treatment of the free-bound continuum has also been updated.