Objects where Si is detected at levels consistent with radiative levitation (red circles), and objects where Si is neither detected, nor expected to be radiatively supported for their T_eff and log  g (green crosses). The blue squares indicate the parameters of eight stars where radiative levitation is strong enough to produce visible lines, yet, no metals are detected in their COS spectra. The black continuous line indicates the location for an EW of 30 mÅ of the Si ii 1265 line, which is our detection threshold.