Ly-α line profile of Kepler-444A. The green line shows the theoretical intrinsic stellar emission line profile scaled to the Earth distance. The absorption profiles of the two ISM components toward Kepler-444 A are plotted as dashed blue lines, with their cumulated profile shown as a dashed black line. The solid blue line shows the Ly-α line profile after absorption by the ISM. The solid black line shows its convolution with STIS LSF, before its comparison to the out-of-transit spectrum shown as a red histogram. The hatched region was excluded from the fit. The right axis shows the ratio β between radiation pressure and stellar gravity.