<div>The estimation of spectral parameters of M dwarfs, which are critical information as planet-hosting environment, has been conducted mainly by comparing the stellar spectra with spectral models with physical assumptions. However, due to effects such as the large number of molecular lines that appear at low temperatures, there are known differences between observed spectra and models, or between several state-of-the-art models. We have applied ExoJAX (<a href="https://github.com/HajimeKawahara/exojax">https://github.com/HajimeKawahara/exojax</a>), which is being developed for exoplanet atmospheric retrieval, to the high-resolution spectrum of the well-known M dwarf Barnard's star (Subaru/IRD). The results show that the best-fit spectra reproduced well the absorption features of molecules and atoms simultaneously in some wavelength regions, and estimated the temperature-pressure structure and abundances of each atom and molecular species. We also confirmed that the same procedure cannot reproduce the data in some wavelength ranges, and discussed absorption lines that are missing in the latest absorption line database. The close examination of the atmospheric retrieval method for M dwarfs is significant both in the search for a new characterization method for M dwarfs and in the hotter-temperature validation of the method for planetary mass objects for which high-quality spectra can be obtained.</div>
[Poster PDF File]