Doubts about VLTI results

• based on fit of an ellipse to observed squared visibilities V2 translated to equivalent uniform disk angular diameters

  • ambiguous meaning of “radius” for stars with extended atmospheres: effects of limb darkening, wavelength dependence, and (for rapid rotators) gravity darkening
  • interferometer response functions depend on polarization

• the two axes were calibrated with two different stars

• polarization history of Achernar