LIMB-DARKENING AND RADII OF NON-MIRA M-GIANT MODELS

Monochromatic limb-darkening and monochromatic radii predicted by the non-Mira M giant models of Bessell et al. (1989a, 1991) with 3500 K gr eater than or equal to T-eff greater than or equal to 2500 K were comp uted for selected typical bandpasses used in interferometric and lunar occultation work. Problems of defining and measuring radii of extende d-photosphere stars and the relationship between different assumptions on limb-darkening and 'measured' radii are discussed. Fits of simple uniform disk (UD), fully darkened disk (FDD) and Gaussian limb-darkeni ng curves to the visibilities predicted by the non-Mira M giant models were performed. These fits show that the FDD curve is often a surpris ingly good approximation to the model-predicted limb-darkening shape.