The FERRUM Project
Abstract
The FERRUM project aims at improving the database for oscillator strengths in iron group elements with an emphasis on astrophysically important ions. The international collaboration includes experts on experimental, theoretical and observational data. The first results concern Fe II. Experimental radiative lifetimes (LIF technique) for some particular levels of Fe II are combined with experimental (FT spectroscopy) and theoretical branching fractions to obtain absolute oscillator strengths, which are then compared with new theoretical data (orthogonal operator technique). Depending on the agreement complementary theoretical data are included. The new data are tested in stellar spectra (HST, NOT). We have obtained f-values for Fe II lines in the UV and optical regions originating from lower levels with excitation energies in the range 3-10 eV. The lines belong to four different transition arrays. The difference between experimental and theoretical data is of the order of 10%. The new data provide independent and new lines for abundance analysis and a test of LTE conditions in stellar atmospheres. Lifetimes of metastable states are measured at a storage ring, providing the first experimental data for forbidden lines, [Fe II].
- Publication:
-
IAU Joint Discussion
- Pub Date:
- 2000
- Bibcode:
- 2000IAUJD...1E..20J