The FERRUM project aims at improving the database for oscillator strengths in iron group elements... 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
The NASA plans for FUSE, a satellite which obtains spectra with resolutions between 100,000 and 1... 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
Journal of Physics B: Atomic, Molecular and Optical Physics, 1995
ABSTRACT Theoretical oscillator strengths for transitions between the even 4s24p2 and the three o... more ABSTRACT Theoretical oscillator strengths for transitions between the even 4s24p2 and the three odd (4s4p3, 4s24p4d, 4s24p5s) configurations of As+ are reported. Both ab initio, multiconfiguration Hartree-Fock and semiempirical configuration interaction techniques are used. The uncertainty of the results are estimated, by considering the reproduced energy structure, the agreement of results from the two methods and cancellation effects in the transition elements. For the strongest transitions the estimated uncertainty is about 10%.
Aims. We present new and improved radiative lifetimes for eight levels in Hf I and 18 levels in H... 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
The heavy elements, platinum, gold, mercury, and thallium, which are apparently overabundant by f... 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
... hrs.gsfc.nasa.gov. 5 Department of Physics and Astronomy, State University of New York at Sto... more ... hrs.gsfc.nasa.gov. 5 Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, NY 11794-3800; [email protected], [email protected]. 6 Center for Astrophysics ...
The FERRUM project aims at improving the database for oscillator strengths in iron group elements... 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
The NASA plans for FUSE, a satellite which obtains spectra with resolutions between 100,000 and 1... 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
Journal of Physics B: Atomic, Molecular and Optical Physics, 1995
ABSTRACT Theoretical oscillator strengths for transitions between the even 4s24p2 and the three o... more ABSTRACT Theoretical oscillator strengths for transitions between the even 4s24p2 and the three odd (4s4p3, 4s24p4d, 4s24p5s) configurations of As+ are reported. Both ab initio, multiconfiguration Hartree-Fock and semiempirical configuration interaction techniques are used. The uncertainty of the results are estimated, by considering the reproduced energy structure, the agreement of results from the two methods and cancellation effects in the transition elements. For the strongest transitions the estimated uncertainty is about 10%.
Aims. We present new and improved radiative lifetimes for eight levels in Hf I and 18 levels in H... 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
The heavy elements, platinum, gold, mercury, and thallium, which are apparently overabundant by f... 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
... hrs.gsfc.nasa.gov. 5 Department of Physics and Astronomy, State University of New York at Sto... more ... hrs.gsfc.nasa.gov. 5 Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, NY 11794-3800; [email protected], [email protected]. 6 Center for Astrophysics ...
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