Elemental abundances of M dwarfs based on high-resolution near-infrared spectra: Extension of verification by binary systems

M dwarfs are the prominent targets of planet search projects, while the complexity of their spectra has limited the understanding of their individual elemental abundances. We have been developing a method to determine the abundances of Na, Mg, Si, K, Ca, Ti, V, Cr, Mn, Fe, and Sr from the near-infrared high-resolution spectra of M dwarfs. This was previously applied to the targets of the IRD planet survey (Subaru Telescope) to show that the abundance distributions were consistent with the Galactocentric space velocities calculated with Gaia astrometry (Ishikawa et al. 2022). The method was verified by Ishikawa et al. (2020) using the CARMENES archive data of five M dwarfs that have G- or K-type binary companions with known composition. However, verification at a lower temperature range has been required. We have observed eight M dwarfs including those with effective temperature (Teff) down to 3000 K in binary systems with hotter primary stars with the CARMENES or the IRD. We present that the results of the most abundances agree with those of primaries. We also investigated the sensitivity of the FeH lines to Teff and estimated the Teff of M dwarfs using them as the Teff indicators. The Teff values derived from the FeH line share a common trend among the IRD planet-survey targets with the literature values, such as the Teff estimated from the Gaia color, and have smaller statistical errors