In Figs A.1–A.3, we fit a Gaussian curve for the visibility drop in the Hα line. The left panel presents, as a function of the reduced heliocentric Julian date, the size in mas of the Hα region deduced from the minimum of visibility and modeled as a Gaussian function. In the middle panel we show the evolution of the velocity shift for the minimum of visibility (△ ) overplotted with the radial velocity determined by spectroscopy directly (+ signs). The solid line represents the radial velocity of the F star orbital motion. In the right panel, the width in velocity of the visibility drop is displayed. In all 3 panels, the horizontal scale is the reduced heliocentric Julian date.