Comparison between several models and the HARPS data set. Orange line: BF-HST. The sodium line cores absorption is too low to reproduce the high-resolution data set. Blue line: Aerosol-free model. This model reproduces better the high-resolution data set, but is not consistent with the low-resolution data set. Green line: 10Na. Our rigorous wavelength normalization process means it is indistinguishable from the aerosol-free model. It is, however, penalized compared to the previous model due to the presence of three additional parameters to describe aerosols. Red line: HTT. A higher thermospheric temperature increases the scale height of the outermost layers, and makes the sodium cores sharper.