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We have reanalyzed SUMER observations of a parcel of coronal gas using newcollisional ionization equilibrium (CIE) calculations. These improved CIEfractional abundances were calculated using state-of-the-art electron-ionrecombination data for K-shell, L-shell, Na-like, and Mg-like ions of allelements from H through Zn and, additionally, Al- through Ar-like ions of Fe.They also incorporate the latest recommended electron impact ionization datafor all ions of H through Zn. Improved CIE calculations based on theserecombination and ionization data are presented here. We have also developed anew systematic method for determining the average emission measure ($EM$) andelectron temperature ($T_e$) of an isothermal plasma. With our new CIE data andour new approach for determining average $EM$ and $T_e$, we have reanalyzedSUMER observations of the solar corona. We have compared our results with thoseof previous studies and found some significant differences for the derived $EM$and $T_e$. We have also calculated the enhancement of coronal elementalabundances compared to their photospheric abundances, using the SUMERobservations themselves to determine the abundance enhancement factor for eachof the emitting elements. Our observationally derived first ionizationpotential (FIP) factors are in reasonable agreement with the theoretical modelof Laming (2008).

astrophysical journal/the astrophysical journal

A new approach to analyzing solar coronal spectra and updated  collisional ionization equilibrium calculations. II. Additional ionization  rate coefficients