Effects of rotation on the colours and line indices of stars. IV - The effect on broad band UBV colours

Abstract

The effect of rotation on UBV photometry is estimated. The relationship between (U-B) and (u-b) and also (B-V) and (b-y) are established using the standard stars photometry to compare the observed effects with theoretical predictions. The observed effects of rotation in Alpha Persei, Pleiades, and Scorpio-Centaurus association are in excellent agreement with models of Collins and Sonneborn (1977) but disagree with the calculations by Maeder and Peytremann (1970). The slopes of the observed reddening per 100 km/s of V sin i in (U-B) and (B-V) for B5 to B9 stars are 0.042 +/-0.005 and 0.011 +/-0.001, respectively.