Positions in HRD of our entire sample. Stars with Gaia DR2 parallaxes are shown by black open symbols (circles and crosses for parallaxes better or worse than than 10%, respectively); blue symbols are stars with New HIPPARCOS parallaxes only (all better than 10%). Input parameters from the different catalogues used for the determination of the stellar luminosities and effective temperatures are described in Sects. 2.2 and 3.2 respectively.