Elemental Abundances of nearby M Dwarfs Based on High-resolution Near-infrared Spectra Obtained by the Subaru/IRD Survey: Proof of Concept

Ishikawa, Hiroyuki Tako; Aoki, Wako; Hirano, Teruyuki; Kotani, Takayuki; Kuzuhara, Masayuki; Omiya, Masashi; Hori, Yasunori; Kokubo, Eiichiro; Kudo, Tomoyuki; Kurokawa, Takashi; Kusakabe, Nobuhiko; Narita, Norio; Nishikawa, Jun; Ogihara, Masahiro; Ueda, Akitoshi; Currie, Thayne; Henning, Thomas; Kasagi, Yui; Kolecki, Jared R.; Kwon, Jungmi; Machida, Masahiro N.; McElwain, Michael W.; Nakagawa, Takao; Vievard, Sebastien; Wang, Ji; Tamura, Motohide; Sato, Bun'ei
Bibliographical reference

The Astronomical Journal

Advertised on:
2
2022
Number of authors
27
IAC number of authors
1
Citations
15
Refereed citations
13
Description
Detailed chemical analyses of M dwarfs are scarce but necessary to constrain the formation environment and internal structure of planets being found around them. We present elemental abundances of 13 M dwarfs (2900 < T eff < 3500 K) observed in the Subaru/IRD planet search project. They are mid- to late-M dwarfs whose abundance of individual elements has not been well studied. We use the high-resolution (~70,000) near-infrared (970-1750 nm) spectra to measure the abundances of Na, Mg, Si, K, Ca, Ti, V, Cr, Mn, Fe, and Sr by the line-by-line analysis based on model atmospheres, with typical errors ranging from 0.2 dex for [Fe/H] to 0.3-0.4 dex for other [X/H]. We measure radial velocities from the spectra and combine them with Gaia astrometry to calculate the Galactocentric space velocities UVW. The resulting [Fe/H] values agree with previous estimates based on medium-resolution K-band spectroscopy, showing a wide distribution of metallicity (-0.6 < [Fe/H] < +0.4). The abundance ratios of individual elements [X/Fe] are generally aligned with the solar values in all targets. While the [X/Fe] distributions are comparable to those of nearby FGK stars, most of which belong to the thin-disk population, the most metal-poor object, GJ 699, could be a thick-disk star. The UVW velocities also support this. The results raise the prospect that near-infrared spectra of M dwarfs obtained in the planet search projects can be used to grasp the trend of elemental abundances and the Galactic stellar population of nearby M dwarfs.
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