Research Interests:
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... more
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
Research Interests:
Research Interests:
The NASA plans for FUSE, a satellite which obtains spectra with resolutions between 100,000 and 100 in the spectral regions from 912 to 1216A and 100 to 912A, are outlined. Scientific problems which can be tackled by FUSE, but not by IUE... more
The NASA plans for FUSE, a satellite which obtains spectra with resolutions between 100,000 and 100 in the spectral regions from 912 to 1216A and 100 to 912A, are outlined. Scientific problems which can be tackled by FUSE, but not by IUE or the Space Telescope, are discussed. A grazing incidence echelle and a hybrid echelle design are presented. They
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Aims. We present new and improved radiative lifetimes for eight levels in Hf I and 18 levels in Hf II, along with oscillator strengths and wavelengths for 195 transitions in Hf II. With these data we determine the abundance of hafnium in... more
Aims. We present new and improved radiative lifetimes for eight levels in Hf I and 18 levels in Hf II, along with oscillator strengths and wavelengths for 195 transitions in Hf II. With these data we determine the abundance of hafnium in two chemically peculiar stars: the hot-Am star HR 3383 and the HgMn star chi Lupi, and discuss the
Research Interests:
The heavy elements, platinum, gold, mercury, and thallium, which are apparently overabundant by factors of 10(3) --10(5) in many peculiar B stars, also can show strong ionization anomalies, with abundances as determined from different... more
The heavy elements, platinum, gold, mercury, and thallium, which are apparently overabundant by factors of 10(3) --10(5) in many peculiar B stars, also can show strong ionization anomalies, with abundances as determined from different ionization stages differing by as much as 1 dex. It is currently unclear whether such ionization anomalies are simply the result of non-LTE effects, or if