Determination of spectroscopic parameters for 313 M dwarf stars from their APOGEE Data Release 16

Context. Interest has been growing among the scientific community with respect to the stellar parameters of M dwarfs in recent years, with potential applications ranging from galactic characterization to exoplanet detection.Aims. The main motivation for this work is to develop an alternative and objective method for deriving stellar parameters for M dwarfs using the H-band spectra provided by the Apache Point Observatory Galactic Evolution Experiment (APOGEE).Methods. We took synthetic spectra generated with iSpec, Turbospectrum, MARCS model atmospheres, along with a custom line list that includes over 1 000 000 water lines, and we compared the data to APOGEE observations, with parameters that were determined through chi (2) minimization.Results. We present spectroscopic parameters (T-eff, [M/H], log g, v(mic)) for a sample of 313 M dwarfs obtained from their APOGEE H-band spectra. The generated synthetic spectra reproduce observed spectra to a high level of accuracy. The impact of the spectra normalization on the results are analyzed as well.Conclusions. We compared our output parameters with those obtained with the APOGEE Stellar Parameter and Chemical Abundances Pipeline for the same stellar spectrum and we find that the values agree within the expected uncertainties. Comparisons with other previous near-infrared and optical data from the literature are also available, with median differences within our estimated uncertainties found in most cases. Here, we explore possible reasons for these differences. The full H-band line list, the line selection for the synthesis, and the synthesized spectra are available for download, along with the calculated stellar parameters.