Chianti - An atomic database for emission lines. IV. Extension to X-ray wavelengths

CHIANTI provides a database of atomic energy levels, wavelengths, radiative transition probabilities, and electron excitation data for a large number of ions of astrophysical interest. It also includes a suite of Interactive Data Language programs to calculate optically thin synthetic spectra and to perform spectral analysis and plasma diagnostics. This database allows the calculation of theoretical line emissivities necessary for the analysis of optically thin emission-line spectra. The first version (1.01) of the CHIA NTI database was released in 1996 and published by Dere et al. in 1997 as P aper I in this series. The second version, released in 1999 by Landi et al. , included continuum emission and data for additional ions. Both versions o f the CHIANTI database have been used extensively by the astrophysical and solar communities to analyze emission-line spectra from astrophysical sourc es. Now the CHIANTI database has been extended to wavelengths shorter than 50 Angstrom by including atomic data for the hydrogen and helium isoelectro nic sequences, inner-shell transitions and satellite lines, and several oth er ions. In addition, some of the ions already present in the database have been updated and extended with new atomic data from published calculations .