[Mg/Si] vs. [Fe/H]. The blue square gives the position of the star hosting the planet with the lowest mass in the sample: HAT-P-26. The other labeled stars are those with [Fe/H] < 0.0 or with [Mg/Si] < −0.1. Mean errors on [Mg/H], [Si/H], and [Fe/H] are similar to each other (~0.07 dex). Overplotted in gray are the results by Adibekyan et al. (2015) for stars hosting low-mass planets (squares) and high-mass planets (circles).