  Weak line emission originating in the photosphere is well known from O stars
and widely used for luminosity classification. The physical origin of the line
emission are NLTE effects, most often optical pumping by far-UV lines.
Analogous lines in B stars of lower luminosity are identified in radially
pulsating $\beta$ Cephei stars. Their diagnostic value is shown for radially
pulsating stars, as these lines probe a much larger range of the photosphere
than absorption lines, and can be traced to regions where the pulsation
amplitude is much lower than seen in the absorption lines.
