Ryan C. Terrien, Suvrath Mahadevan, Chad F. Bender, Rohit Deshpande, Lawrence W. Ramsey, John J. Bochanski
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 super-solar 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.
View original:
http://arxiv.org/abs/1202.1800
No comments:
Post a Comment