On application of multi-colour photometry of $\delta$ Scuti stars

Abstract

In $\delta$ Scuti star models, the photometric amplitudes and phases exhibit a strong dependence on convection, which enters through the complex parameter, $f$, which describes the bolometric flux variation. We present a new method of extracting simultaneously $\ell$ and $f$ from multi-colour data and apply it to several $\delta$ Scuti stars. The inferred values of $f$ are sufficiently accurate to yield an useful constraint on models of stellar convection. In addition, if the identified mode is radial, the multi-passband data may be used to refine global stellar parameters. Finally, the usage of radial velocity measurements to our method improves significantly determination of $\ell$ and $f$.

4 pages, 3 figures to appear in Proceedings of IAU Colloquium 193, Variable Stars in the Local Group, July 2003, Christchurch, New Zealand, ASP Conf. Ser., eds. D. W. Kurtz & K. Pollard