UBV observations of post-AGE supergiants and peculiarities of their photometric variability

The systematic UBV observations of six variable post-AGE supergiants in 199 1-1999 are presented. Their variability is analyzed. The coolest stars V102 7 Cyg acid V354 Lac exhibit bimodal pulsations with variable amplitudes. Ap art from pulsations, the hotter stars V887 Her and IRAS 19386+0155 show lig ht variations associated with a stellar wind. A variable stellar wind appea rs to be mainly responsible for the photometric variations in the still hot ter stars SAO 163075 and IRAS 20572+4919. Distinct trends in the yearly mea n brightness have been found in three of the six supergiants studied, with the trend amplitude being independent of the spectral range. They are inter preted as the result of dust envelopes composed of large grains with R = A( V)/E(B-V) greater than or equal to 7 becoming optically thin. (C) 2000 MAIK "Nauka/Interperiodica".