The cloudy circumstellar dust shell of WW Vulpeculae revisited.

WW Vulpeculae is an evolutionarily young and irregular variable star coinciding with the infrared point source IRAS 19238 + 2106. The most conspicuous features of the lightcurve are the aperiodically occurring Algol-like minima with amplitudes up to 1.5 mag. Relevant UBVR data show that these minima originate from individual dust clouds moving in a circumstellar dust shell. The photometric data indicate different optical properties of the grain populations in these dust clouds. The reddening parameter R = A V /E(B − V) has been found to vary in the range from 3.5 to 7 for the individual clouds observed. The observed infrared excess supports the circumstellar origin of the optical variability