Accessible semi-major axis of the hypothetical additional planet β Pic d, prior to simulations, as a function of its eccentricity. Shaded areas are not accessible by β Pic d. Its semi-major axis must be smaller than the inner edge of the disk at 50 au (solid black line) to sculpt it up to this distance, while being greater than the stability limit with β Pic b (dashed black line) to avoid close encounters, based on the criterion of Petrovich (2015).