APOGEE: M dwarfs metallicity & planet parameters

In this study, we derived stellar metallicities and oxygen abundances for 48 M dwarf stars using the near-infrared high-resolution spectra from the SDSS APOGEE survey and synthetic spectra computed in LTE. We also investigated the exoplanetary radii distribution for a larger sample of 246 exoplanets orbiting 188 M dwarf stars.

The [M/H] versus [O/M] distribution obtained indicates that our sample is composed mainly of thin disk stars, which follow the behavior of the low-alpha sequence in the Milky Way thin disk. Small planets with radii smaller than 3R_{Earth}_ were found around stars with a range of metallicities (-0.6<[M/H]<+0.3), while larger planets of the sample orbit only stars with [M/H]>=0.0. These results indicate that while small planets can form in different environments, larger planets preferentially form in metal-rich protoplanetary disks.