Abstract
We have analyzed a high-resolution and high-S/N UVES spectrum of the Bp star a Centauri (He-variable) by means of state-of-the-art non-LTE spectral synthesis. Atmospheric parameters were determined in an iterative way via ionization equilibria of OI/II and FeII/III and the matching of several Balmer lines simultaneously. Because of chemical stratification and the presence of ^{3}He, the He lines are not matched with a standard model atmosphere. A new He model atom accounting for the ^{3}He isotope and an empirically solution for the He stratification in the line-formation calculations allow us to characterize this star in a more realistic manner than do classical models.
