AN H-band spectroscopic metallicity calibration for M dwarfs

Ryan C. Terrien, Suvrath Mahadevan, Chad F. Bender, Rohit Deshpande, Lawrence W. Ramsey, John J. Bochanski

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Abstract

We present an empirical near-infrared (NIR) spectroscopic method for estimating M dwarf metallicities, based on features in the H band, as well as an implementation of a similar published method in the K band. We obtained R 2000 NIR spectra of a sample of M dwarfs using the NASA IRTF-SpeX spectrograph, including 22 M dwarf metallicity calibration targets that have FGK companions with known metallicities. The H-band and K-band calibrations provide equivalent fits to the metallicities of these binaries, with an accuracy of ±0.12 dex. We derive the first empirically calibrated spectroscopic metallicity estimate for the giant planet-hosting M dwarf GJ 317, confirming its supersolar metallicity. Combining this result with observations of eight other M dwarf planet hosts, we find that M dwarfs with giant planets are preferentially metal-rich compared to those that host less massive planets. Our H-band calibration relies on strongly metallicity-dependent features in the H band, which will be useful in compositional studies using mid- to high-resolution NIR M dwarf spectra, such as those produced by multiplexed surveys like SDSS-III APOGEE. These results will also be immediately useful for ongoing spectroscopic surveys of M dwarfs.

Original languageEnglish (US)
Article numberL38
JournalAstrophysical Journal Letters
Volume747
Issue number2
DOIs
StatePublished - Mar 10 2012

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Terrien, R. C., Mahadevan, S., Bender, C. F., Deshpande, R., Ramsey, L. W., & Bochanski, J. J. (2012). AN H-band spectroscopic metallicity calibration for M dwarfs. Astrophysical Journal Letters, 747(2), [L38]. https://doi.org/10.1088/2041-8205/747/2/L38