Left: determination of the stellar metallicity of KOI-2133 (see Sect. 3.4.1). We show data from giants compiled by Gray et al. (2002) to parametrize the line absorption parameter (LA) with the iron abundance [Fe/H]. Two samples are shown: giants with T_eff > 4830 K (red) and giants with T_eff < 4830 K (blue). Solid lines represent the fitted second-order polynomials to the test data. The dotted vertical line shows the obtained LA for KOI-2133 and the black circle its determined position in the diagram. Right: effective temperature versus LA showing that KOI-2133 should be considered in the cool group of giants regarding the left panel segregation. The red circles show the position of the test giants, and the dashed line represents an estimated empirical limit to the temperature for each LA.