Power-law-type limb-darkened disk fit to the AMBER data of W Hya. a) Limb-darkened disk diameter. The scaled observed spectrum of W Hya is shown by the black solid line. b) Limb-darkening parameter α. The black solid line represents the scaled observed spectrum with a vertical shift shown by the dashed line. c) Observed visibilities in the continuum, CO line, and CO band head are shown by the dots, while the visibilities from the limb-darkened disk fit are plotted by the solid lines. d) Limb-darkened disk intensity profiles in the continuum, CO line, and CO band head.