Astronomers have discovered a planetary system orbiting the star Upsilon Andromedae, which is at a distance of 4.2 × 1017 m from the earth. One planet is believed to be located at a distance of 1.2 × 1011 m from the star. Using visible light with a vacuum wavelength of 550 nm, what is the minimum necessary aperture diameter that a telescope must have so that it can resolve the planet and the star?