The author expresses her gratitude to H. Holweger for suggesting this work and for numerous discussions. Thanks are also due to M. Lemke for making the VCS tables available and to T. Rauch for helping with the computations. The author is grateful to H. Holweger for providing the ESO spectra and to J. Babel for providing an unpublished infrared spectrum of Vega. Support from a graduate student fellowship from Schleswig-Holstein is also acknowledged.
© European Southern Observatory (ESO) 1997