We obtain high-precision limb-darkening measurements in five bands ( V , V _ { E } , I _ { E } , I , and H ) for the K3 III ( T _ { eff } = 4200 { K } , [ Fe/H ] = +0.3 , \log g = 2.3 ) source of the Galactic bulge microlensing event EROS BLG-2000-5 .
These measurements are inconsistent with the predictions of atmospheric models at > 10 \sigma .
While the disagreement is present in all bands , it is most apparent in I , I _ { E } and V _ { E } , in part because the data are better and in part because the intrinsic disagreement is stronger .
We find that when limb-darkening profiles are normalized to have unit total flux , the I -band models for a broad range of temperatures all cross each other at a common point .
The solar profile also passes through this point .
However , the profile as measured by microlensing does not .
We conjecture that the models have incorporated some aspect of solar physics that is not shared by giant atmospheres .