New Zr II oscillator strengths and the zirconium conflict in the HgMn starchi Lupi

Lifetimes on the sub-nanosecond scale for the levels v(2)D(3/2), v(2)F(3/2) and v(2)F(5/2) in the 4d5s5p configuration in Zr II have been measured, us ing the method of laser-induced fluorescence. Combined with branching fract ions obtained with the Lund Ultraviolet (UV) Fourier Transform Spectrometer (FTS), experimental oscillator strengths have been derived. From Hubble Sp ace Telescope/Goddard High-Resolution Spectrograph spectra, the zirconium a bundance in the HgMn star chi Lupi has been determined from Zr II and Zr II I lines. More than an order of magnitude difference in the Zr II abundance has been derived from these ionization stages. The difference is much too l arge to be explained by uncertainties in the oscillator strengths. Possible explanations of this difference have to be found in the stellar models, su ch as the influence of non-LTE or diffusion.