Name/Affiliation: Sara Lindgren, Ulrike Heiter, Bengt Edvardsson and Andreas Seifahrt (Uppsala university)
Accurate metallicity determination of M dwarfs
Accurate knowledge of the composition of M dwarfs is essential for advancing the understanding of e.g. planet formation and the galactic evolution. However, due to their intrinsic faintness and low surface temperature these stars are a spectroscopic challenge. In the infrared the number of molecular transitions is greatly reduced, allowing an accurate continuum placement and thereby a great improvement in the reliability of the abundance determination for M dwarfs. We continue the work by Önehag et al., 2012, using high-resolution spectra taken in the J band with the CRIRES spectrograph. To affirm the reliability of the method we analyzed two M dwarfs in close binary systems with hotter companion stars. The study will be extended to a sample of additionally 22 M dwarfs (not in binary systems) to get a good coverage in Teff and metallicity. With the results we aim at deriving an accurate relationship between photometric color and metallicity, covering most M dwarf subtypes and a metallicity span of approximately ±0.8 dex. The final goal is to use the derived relationship and photometric data from a large sample of M dwarfs to statistically investigate a possible planet – metallicity connection.