Metallicity of M-dwarfs from NIR Spectra

Above solar metallicity, the number of stars with planets and presence of multiple planets increases for solar-type stars (Santos et al. 2001; Fischer & Valenti 2005). M-dwarfs planet hosts known to date have shown abundances below solar metallicity when measured with optical spectra and photometry, suggesting that M-dwarfs have a planetary formation process that differs from F-, G- and K-dwarfs. This could also be due to statistics, with only few M-dwarfs with planetary candidates known, and/or the lack of reliable abundances estimates for this type of star. We present preliminary results from near-infrared spectra of M-dwarf secondaries (with a wide solar type star companion with known metallicity) obtained with the Triple Spec spectrograph operating on the Palomar 200-inch Hale Telescope.