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Abstract. We present recent X-ray and optical observations of five Mtype giants which were detected as strong X-ray sources. One of these stars, HR 5512, shows short-term variations in both X-ray flux as well as in the shape of the Ho and Ca II H+K lines, and it rotates much faster than M-type giants usually do. No indication of binarity has been found for this star. We propose that the X-ray emission of HR 5512 is related to a large degree of stellar activity. For two other stars (15 Tri, HR 7547) radial velocity observations seem to indicate spectroscopic binarity. 223of use, available at https://www.cambridge.org/core/terms. https://doi

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 collected high resolution and high signalto-noise spectra of three giants: HD 232 862, KU Peg and HD 21 018. From spectral synthesis we inferred stellar parameters and measured lithium abundances that we compared to predictions from evolutionary models. We also analysed Stokes V signatures, looking for a magnetic field on these giants. Results. HD 232 862, presents a very high abundance of lithium (A Li = 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 was determined, and it suggests a mass in the lower part of the [1.0 M , 3.5 M ] mass interval, likely 1.5-2.0 M , at the bottom of the red giant branch. Also, a time variable Stokes V signature was 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.

Abstract. EE Cep is an eclipsing binary with a period of 5.6 years. The next eclipse will occur soon, in May-June 2003, and all available past eclipses were collected and briefly analysed. EE Cep shows very large changes of the shape and the depth of minima during different eclipses, however it is possible to single out some persistent features. The analysis suggests that the eclipsing body should be a long object surrounded by an extended semi-transparent envelope. As an explanation, a model of a precessing optically thick disc, inclined to the plane of the binary orbit, is invoked. The changes of its spatial orientation, which is defined by the inclination of the disc and the tilt, induced most probably by precession of the disc spin axis with a period of about 50 years, produce strange photometric behaviour of this star. The Hα emission, and possibly the NaI absorptions, show significant changes during several months outside of the eclipse phase.