Fig. 8. Wavelength difference in velocity units vs. formation temperature. The "wavelength difference" represents the difference between the wavelength observed on the meridian and the one observed at other locations at the same µ. Since the wavelength scale is not absolute, we equalized the wavelengths at the meridian and the equator outside the hole. Diamonds : large µ sector (identically zero due to equalization); Stars : small µ sector (i.e., shift of hole profile relative to non-hole profiles). The solid curve shows a second order polynomial fit to the small µ sector points. Negative shifts signify blueshifts.