Multiplicity studies greatly benefit from focusing on M dwarfs because they are often paired in a variety of configurations with both stellar and substellar objects, including exoplanets. We aim to address the observed multiplicity of M dwarfs by conducting a systematic analysis using the latest available astrophotometric data. For every star in a sample of 2214 M dwarfs from the CARMENES catalogue, we investigated the existence of resolved and unresolved physical companions in the literature and in all-sky surveys, especially in the Gaia DR3 data products. We covered a very wide range of separation, from known spectroscopic binaries in tight arrangements (~0.01au) to remarkably separated ultrawide pairs (~10^5au). We identify 835 M dwarfs in 720 multiple systems, predominantly binaries, and proposing 327 new binary candidates based on Gaia data. If these candidates are finally confirmed, we expect the multiplicity fraction of M dwarfs to be 40.3^+2.1^_-2.0_%. Only considering the systems already identified, the multiplicity fraction is reduced to 27.8^+1.9^_-1.8_%, which is in line with most of the values published in the literature. We also identify M-dwarf multiple systems with FGK, white dwarf, ultracool dwarf, and exoplanet companions, and in young stellar kinematic groups, and study physical separations, orbital periods, binding energies, and mass ratios. We argue that, based on reliable astrometric data and spectroscopic investigations from the literature,and even when considering detection biases, the multiplicity fraction of M dwarfs could still be significantly underestimated, encouraging further high-resolution follow-up studies.

Multiplicity status for 2214 M dwarfs based on high-quality astrometric data from Gaia DR3, with a detailed characterisation of the systems, including orbital properties such as physical separations, periods and binding energies. Astrophysical parameters are tabulated, including stellar masses, radii, effective temperatures, and luminosities. Criteria for identifying unresolved binary candidates based on Gaia statistical products are provided, offering a foundation for deeper follow-up studies on multiplicity.

Peer reviewed