Detailed Chemical Abundances for a Benchmark Sample of M Dwarfs from the
  APOGEE Survey
  Individual chemical abundances for fourteen elements (C, O, Na, Mg, Al, Si,
K, Ca, Ti, V, Cr, Mn, Fe, and Ni) are derived for a sample of M-dwarfs using
high-resolution near-infrared $H$-band spectra from the SDSS-IV/APOGEE survey.
The quantitative analysis included synthetic spectra computed with 1-D LTE
plane-parallel MARCS models using the APOGEE DR17 line list to determine
chemical abundances. The sample consists of eleven M-dwarfs in binary systems
with warmer FGK-dwarf primaries and ten measured interferometric angular
diameters. To minimize atomic diffusion effects, [X/Fe] ratios are used to
compare M-dwarfs in binary systems and literature results for their warmer
primary stars, indicating good agreement ($<$0.08 dex) for all studied
elements. The mean abundance differences in Primaries-this work M-dwarfs is
-0.05$\pm$0.03 dex. It indicates that M-dwarfs in binary systems are a reliable
way to calibrate empirical relationships. A comparison with abundance,
effective temperature, and surface gravity results from the ASPCAP pipeline
(DR16) finds a systematic offset of [M/H], $T_{\rm eff}$, log$g$ = +0.21 dex,
-50 K, and 0.30 dex, respectively, although ASPCAP [X/Fe] ratios are generally
consistent with this study. The metallicities of the M dwarfs cover the range
of [Fe/H] = -0.9 to +0.4 and are used to investigate Galactic chemical
evolution via trends of [X/Fe] as a function of [Fe/H]. The behavior of the
various elemental abundances [X/Fe] versus [Fe/H] agrees well with the
corresponding trends derived from warmer FGK-dwarfs, demonstrating that the
APOGEE spectra can be used to Galactic chemical evolution using large samples
of selected M-dwarfs.
