Photometry and Velocity of 3 {zeta} Aur binaries

Our concurrent photometry detected the nonradial pulsations driven by tides (ellipsoidal variation) in both {zeta} Aur and 32 Cyg, at a level and phasing roughly consistent with simple theory to first order, although they seem to require moderately large gravity darkening.

We point out two fundamental questions in the interpretation of these stars: (1) whether it is appropriate to model the surface brightness as gravity darkening and (2) whether much of the nonorbital velocity structure may actually represent changes in the convective flows in the stars' atmospheres.