Abstract. We present the results of high-precision UBV (RI) c photometric observations and of spectroscopic radial velocity measurements obtained at the European Southern Observatory for a sample of 51 cool stars detected in the EUV by the ROSAT Wide Field Camera (WFC). Using also recent results from HIPPARCOS, we infer spectral types and investigate the single or binary nature of the sample stars. Optical variability, with periods in the 0.4-13 day range, has been detected for the first time in 15 of these stars.

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Abstract. The Catalogue, available at the Centre de Données Stellaires de Strasbourg , consists of 13 573 records concerning the results obtained from different methods for 7778 stars, reported in the literature. The following data are listed for each star: identifications, apparent magnitude, spectral type, apparent diameter in arcsec, absolute radius in solar units, method of determination, reference, remarks. Comments and statistics obtained from CADARS are given.

Abstract. We present an analysis of our high-resolution spectroscopic and high-precision UBV(RI) c photometric observations of a sample of 110 nearby late-F and G-type stars selected for their large rotational velocity. The relationships between Li abundance, X-ray luminosity, and v sin i are investigated. We find that, as expected, the stars in our sample show statistically higher Li abundance and activity level than field star samples with similar characteristics, but slower rotation. Surprisingly, however, we also find four rapidly-rotating single main-sequence stars with very low Li abundance. For both single and binary stars we find a large spread of Li abundance for stars with rotation lower than about 18 km s −1 . The well-established correlation between X-ray luminosity and rotation rate is clearly observed. All single unevolved solar type stars with v sin i larger than 18 km s −1 are strong X-ray emitters and have high Li abundance. Finally, we find also five evolved stars with very low Li abundance that are still rather fast rotators. The results from our sample confirm the presence of young very active stars close to the Sun, in agreement with recent findings from EUV and X-ray surveys, although our sample does not show such extreme characteristics as those selected from EUV and X-ray surveys at the current flux limits.

Context. Measurements of lithium (Li) abundances in open clusters provide a unique tool for following the evolution of this element with age, metallicity, and stellar mass. In spite of the plethora of Li data already available, the behavior of Li in solar-type stars has so far been poorly understood. Aims. Using FLAMES/Giraffe on the VLT, we obtained spectra of 157 candidate members of the old, metal-poor cluster Berkeley 32, to determine membership and to study the Li behavior of confirmed members. Methods. Radial velocities were measured, allowing us to derive both the cluster velocity and membership information for the sample stars. The Li abundances were obtained from the equivalent width of the Li i 670.8 nm feature, using curves of growth.Results. We obtained an average radial velocity of 105.2 ± 0.86 km s −1 , and 53% of the stars have a radial velocity consistent with membership. The Li -T eff distribution of unevolved members matches the upper envelope of M 67, as well as that of the slightly older and more metal-rich NGC 188. No major dispersion in Li is detected. When considering the Li distribution as a function of mass, however, Be 32 members with solar-like temperature are less massive and less Li-depleted than their counterparts in the other clusters. The mean Li of stars in the temperature interval 5750 ≤ T eff ≤ 6050 K is log n(Li) = 2.47 ± 0.16, less than a factor of two below the average Li of the 600 Myr old Hyades, and slightly above the average of intermediate age (1-2 Gyr) clusters, the upper envelope of M 67, and NGC 188. This value is comparable to or slightly higher than the plateau of Pop. ii stars. The similarity of the average Li abundance of clusters of different age and metallicity, along with its closeness to the halo dwarf plateau, is very intriguing and suggests that, whatever the initial Li abundance and the Li depletion histories, old stars converge to almost the same final Li abundance.