UBV observations of post-AGB supergiants and peculiarities of their photometric variability |
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| Authors: | V P Arkhipova N P Ikonnikova R I Noskova G V Sokol |
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| Institution: | (1) Sternberg Astronomical Institute, Universitetskii pr. 13, Moscow, 119899, Russia |
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| Abstract: | The systematic UBV observations of six variable post-AGB supergiants in 1991–1999 are presented. Their variability is analyzed. The coolest stars V1027 Cyg and V354 Lac exhibit bimodal pulsations with variable amplitudes. Apart from pulsations, the hotter stars V887 Her and IRAS 19386+0155 show light variations associated with a stellar wind. A variable stellar wind appears to be mainly responsible for the photometric variations in the still hotter stars SAO 163075 and IRAS 20572+4919. Distinct trends in the yearly mean brightness have been found in three of the six supergiants studied, with the trend amplitude being independent of the spectral range. They are interpreted as the result of dust envelopes composed of large grains with R=A V /E(B?V)≥7 becoming optically thin. |
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| Keywords: | stars— supergiants variability and evolution |
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