THE CLOUDY CIRCUMSTELLAR DUST SHELL OF WW VULPECULAE REVISITED

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