Roughly speaking, young stars are associated to intense chromospheric activity (CA), whereas it decreases with stellar aging. However, some objects that show high kinematical components – in turn, associated to older stars – reveal CA similar to that of young ones; we call these stars chromospherically young and kinematically old (CYKOs). One hypothesis that could explain their occurrence is the merge of a short-period binary, from which the outcome would be a chromospherically active, kinematically evolved star. Considering that they evolved separately, we expect them to be lithium depleted, and therefore we look for CYKO stars by analyzing their lithium content (λ 6707 Å). We present a preliminary list of 48 stars matching this criteria, aiming to either confirm or discard the coalescence of a short-period pair hypothesis.

Using spectropolarimetric data acquired with the ESPaDOnS and NARVAL instruments at CFHT and at TBL, we present a detailed spectral synthesis analysis of HD 232 862, a field giant classified as a G8II star hosting a magnetic field. This star is the first lithium-rich field giant hosting a magnetic field. Stellar evolution models suggest that HD 232 862 should be a 1.5 to 2.0 M⊙ star at the bottom of the red giant branch. Its unsually high lithium content (A(Li) = 2.45 ± 0.25 dex) is even more puzzling and challenges our understanding of the evolution of this star.

Important results of magnetic CP star research in the last decade from photometric and spectroscopic observations are discussed. Hipparcos parallaxes confirm CP stars are Main Sequence stars. Photometric monitoring of the rapidly rotating stars provides evidences for the rotational braking on the Main Sequence. High signal-to-noise spectra with high resolution and time-resolution give strong support for chemical separation processes operating in stellar atmospheres (abundance stratification). There are also observational evidences for the departure of the temperature structure of cool CP star atmospheres from that for normal stars.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html