Lithium and magnetic fields in giants . HD 232 862 : a magnetic and lithium - rich giant star . ⋆

Aims. We report the detection of an unusually high lithium content in HD 232 862, a field giant classified as a G8II star, and hosting a magnetic field. Methods. With the spectropolarimeters ESPaDOnS at CFHT and NARVAL at TBL, we have collected high resolution and high signal-to-noise spectra of three giants : HD 232 862, KU Peg and HD 21 018. From spectral synthesis we have inferred stellar parameters and measured lithium abundances that we have compared to predictions from evolutionary models. We have also analysed Stokes V signatures, looking for a magnetic field on these giants. Results. HD 232 862, presents a very high abundance of lithium (ALi = 2.45 ± 0.25 dex), far in excess of the theoretically value expected at this spectral type and for this luminosity class (i.e, G8II). The evolutionary stage of HD 232 862 has been precised, and it suggests a mass in the lower part of the [1.0 M⊙, 3.5 M⊙] mass interval, likely 1.5 to 2.0 M⊙ , at the bottom of the Red Giant Branch. Besides, a time variable Stokes V signature has been detected in the data of HD 232 862 and KU Peg, pointing to the presence of a magnetic field at the surface of these two rapidly rotating active stars.