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arXiv · 2112.00173

Elemental abundances of nearby M dwarfs based on high-resolution near-infrared spectra obtained by the Subaru/IRD survey: Proof of concept

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

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 < Teff < 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 Galactic stellar population of nearby M dwarfs.

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Hiroyuki Tako Ishikawa, Wako Aoki, Teruyuki Hirano, Takayuki Kotani, Masayuki Kuzuhara, Masashi Omiya, Yasunori Hori, Eiichiro Kokubo, Tomoyuki Kudo, Takashi Kurokawa, Nobuhiko Kusakabe, Norio Narita, Jun Nishikawa, Masahiro Ogihara, Akitoshi Ueda, Thayne Currie, Thomas Henning, Yui Kasagi, Jared R. Kolecki, Jungmi Kwon, Masahiro N. Machida, Michael W. McElwain, Takao Nakagawa, Sebastien Vievard, Ji Wang, Motohide Tamura, Bun'ei Sato. 2021-11-30. Elemental abundances of nearby M dwarfs based on high-resolution near-infrared spectra obtained by the Subaru/IRD survey: Proof of concept. https://doi.org/10.3847/1538-3881/ac3ee0

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