New measurement of the 6 Li / 7 Li isotopic ratio in the extra - solar planet host star HD 82943 and line blending in the Li 6708 Å region

The presence of possible blends in the spectral region of the Li resonance line at 6708Å in solar-type metal-rich stars is investigated using high resolution and high signal-to-noise spectroscopic observations. Our analysis does not confirm the identification of a weak absorption feature at 6708.025Å with the low excitation Ti i line proposed by Reddy et al. (2002). Our spectrum synthesis suggests that the unidentified absorption is most probably produced by a high excitation Si i line originally proposed by Müller et al. (1975). Reanalysis of the 6 Li/ 7 Li isotopic ratio in HD 82943 was performed by taking the Si i line into account and using new VLT/UVES spectra of HD 82943 with a signal-to-noise ratio close to 1000. We confirm the presence of 6 Li in the star's atmosphere while the updated value for the isotopic ratio is f (6 Li) = 0.05 ± 0.02.