Are the metal-poor M dwarfs in the solar neighborhood actually from our neighborhood?

Abstract

This work presents metallicities and dynamic analysis for 23 M dwarfs in the solar neighborhood observed by the SDSS-IV APOGEE survey. Assuming the plane-parallel 1D MARCS models, combined with the APOGEE line list and the TurboSpectrum radiative transfer code, we derive the metallicity of our sample to range between –1.00 to –2.00 dex, with effective temperatures ( T _eff ) between 3650 and 4000 K. An analysis of galactic dynamics confirms a halo star pattern for eleven stars in our sample. Since all M dwarfs in this study are located within 350 parsecs of the Sun, we expect these to be transient stars of the halo population, each exhibiting unique characteristics. We identified three stars that likely originated from the Gaia-Enceladus/Sausage (GES) event and one star from the Thamnos merger.