EDP Sciences
Free access
Volume 396, Number 2, December III 2002
Page(s) 715 - 722
Section Atomic and molecular data
DOI http://dx.doi.org/10.1051/0004-6361:20021388

A&A 396, 715-722 (2002)
DOI: 10.1051/0004-6361:20021388

The FERRUM Project: Experimental oscillator strengths of the UV 8 multiplet and other UV transitions from the $\mathsf{y^6}$P levels of Fe II

J. C. Pickering1, M. P. Donnelly2, H. Nilsson3, A. Hibbert2 and S. Johansson3

1  Physics Department, Blackett Laboratory, Imperial College, London SW7 2BZ, UK
2  Department of Mathematics, Queen's University of Belfast, Northern Ireland
3  Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, SE-22100 Lund, Sweden

(Received 13 May 2002 / Accepted 20 September 2002)

We report on experimental branching fractions (BFs) for 19 transitions from the three 3d 5( 6S)4s4p( 3P) y6P levels in Fe II, measured in Fourier transform spectra of a Penning discharge lamp and a hollow cathode lamp. The transition wavelengths span the interval between 1600 and 2850 Å. Absolute oscillator strengths ( f-values) have been derived by combining the BFs with experimental radiative lifetimes recently reported in the literature. Theoretical f-values have been calculated using configuration interaction wavefunctions. The new experimental and theoretical f-values are compared with data available in the literature and in databases. The strongest lines measured belong to the UV 8 multiplet of Fe II, which has one ground state transition appearing as a prominent feature at 1608 Å in interstellar spectra. The line is accompanied by a satellite at 1611 Å due to a level mixing, which is discussed in the paper.

Key words: atomic data -- line: identification -- techniques: spectroscopic -- stars: abundances -- ISM: abundances

Offprint request: J. Pickering, j.pickering@ic.ac.uk

© ESO 2002