Radial Velocity Studies of roAp Stars
  We present recent results from our radial velocity (RV) studies of rapidly oscillating Ap (roAp) stars. Our measurements reveal that the pulsational amplitude of these stars depends on the spectral region that is examined. For one star, gamma Equ, the pulsational RV amplitude depends on both line strength and atomic species. The elemental difference is most likely related to the abundance patches on the surface of these stars. The line strength difference is interpreted as arising form a height effect in the atmosphere. Ultimately, these measurements may provide valuable diagnostics of the atmospheres of these stars. 
A.P. Hatzes (1), A. Kanaan (2) ((1) McDonald Observatory, Texas, USA   (2) UFSM, Brazil)