The photometric effect of rotation in the A stars

Abstract

Previous studies of stellar rotation have been largely confined to the effects on individual stars in rigid rotation. These studies are extended in two ways: (1) detailed stellar atmosphere models are used to compute for the first time the photometric effects of differential as well as rigid rotation; results are given for both the Johnson and the Stromgren systems for late B, A and early F stars; (2) statistical results are obtained for an ensemble of stars in that spectral range, for comparison with the observed properties of galactic clusters. The well-known qualitative result that differential rotation produces a larger scatter in photometric diagrams than does rigid rotation is confirmed, but a number of quantitative subtleties is found that significantly complicate any comparison with observations.