Abundance Measurements of the Metal-poor M Subdwarf LHS 174 Using High-resolution Optical Spectroscopy

Abstract Metal-poor M subdwarfs are among the oldest stellar populations and carry valuable information about the chemical enrichment history of the Milky Way. The measurements of chemical abundances of these stars therefore provide essential insights into the nucleosynthesis in the early stages of the Galaxy’s formation. We present detailed spectroscopic analysis of a nearby metal-poor M subdwarf, LHS 174, from its high-resolution optical spectrum, and apply our previously developed spectral fitting code, AutoSpecFit , to measure the abundances of five elements: [O/H] = −0.519±0.081, [Ca/H] = −0.753 ± 0.177, [Ti/H] = −0.711 ± 0.144, [V/H] = −1.026 ± 0.077, and [Fe/H] = −1.170 ± 0.135. We compare the abundances of O, Ti, and Fe derived from this work and those from previous studies, and demonstrate the observed data are clearly better matched with the synthetic model generated based on our abundances than those from the other analyses. The accuracy of inferred stellar abundances strongly depends on the accuracy of physical parameters, which motivates us to develop a reliable technique to more accurately determine the parameters of low-mass M dwarfs and infer abundances with smaller uncertainties.