Constraints on stellar convection from multi-colour photometry of delta Scuti stars

In Scuti star models, the calculated amplitude ratios and phase dierences for multi-colour photometry exhibit a strong dependence on convection. These observables are tools for the determination of the spherical harmonic degree,' ,o f the excited modes. The dependence on convection enters through the complex parameter f , which describes bolometric flux perturbation. We present a method of simultaneous determination of f and harmonic degree' from multi-colour data and apply it to three Scuti stars. The method indeed works. Determination of' appears unique and the inferred values of f are suciently accurate to yield a useful constraint on models of stellar convection. Furthermore, the method helps to refine stellar parameters, especially if the identified mode is radial.