Astron. Astrophys. 362, 410-418 (2000)

The FERRUM project: new experimental and theoretical f-values for 4p-4d transitions in Fe II applied to HST spectra of Lupi

H. Nilsson ¹, C.M. Sikström ¹, Z.S. Li ², H. Lundberg ², A.J.J. Raassen ⁴, S. Johansson ¹, D.S. Leckrone ³ and S. Svanberg <sup>2

1</sup> Atomic Spectroscopy, Department of Physics, University of Lund, P.O. Box 118, 221 00 Lund, Sweden (hampus.nilsson@fysik.lu.se)
² Department of Physics, Lund Institute of Technology, P.O. Box 118, 221 00 Lund, Sweden
³ NASA/Goddard Space Flight Center, Code 630, Greenbelt, MD 20771, USA
⁴ Astronomical Institute "Anton Pannekoek", University of Amsterdam, Kruislaan 403, 1098 SJ, Amsterdam, The Netherlands

Received 30 May 2000 / Accepted 8 August 2000

Abstract

Radiative lifetimes for six highly excited levels in Fe II have been measured at Lund Laser Centre applying the laser induced fluorescence technique and two-step excitation. The energy levels belong to the even-parity 3d⁶(⁵D)4d subconfiguration at about 10 eV. Branching fractions (BF:s) of 29 transitions from these levels to the 3d⁶(⁵D)4p subconfiguration at about 5 eV have been measured in the wavelength region 2000-3000 Å with the Lund Fourier Transform Spectrometer. By normalizing the BF:s with the lifetimes we get experimental oscillator strengths for these 29 4p-4d lines. The oscillator strengths are compared with new theoretical calculations using the orthogonal operator technique and applied to high-resolution spectra of the star Lupi, recorded with the Hubble Space Telescope .

Key words: atomic data line: identification methods: laboratory ultraviolet: stars stars: individual: O Lupi

Send offprint requests to: H. Nilsson

© European Southern Observatory (ESO) 2000

Online publication: October 30, 19100

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