Low-mass red giants volume-limited samp.

To confirm or discard binarity, we combined astrometric parameters from Gaia with the resulting radial velocity variations. We derived the distribution of stellar parameters using evolutionary models and employed the equivalent evolutionary phase to verify the evolutionary stage of the stars in our sample. Finally, we compared our stellar parameters with the literature.

The derived stellar parameters confirmed that 82% of stars in our sample are indeed in the RGB phase, while 18% are red clump (RC) contaminants. This was expected due to the overlapping of RGB and RC stars in the colour-magnitude diagram. Additionally, 75% of the confirmed RGB stars have a high probability of being part of a binary system.

Comparison with the literature shows good overall agreement with a scatter <~15% in stellar parameters, while the masses show somewhat higher dispersion (~20%). We have obtained the most complete volume-limited sample of binary RGB star candidates within 500 pc. These systems are likely progenitors of hot subdwarfs and other classes of stripped helium stars.