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Paper: New results on spectral and photometric variability of P Cygni
Volume: 233, P Cygni 2000: 400 Years of Progress
Page: 95
Authors: Markova, N.
Abstract: An extensive survey of quasi-simultaneous spectroscopic and photometric data of P Cygni revealed the presence of a close relationship between wind and photospheric activity in this star. Wind variability is diagnosed through variations in line-profile parameters while photospheric variability is detected through changes in the stellar brightness and colour indices. The line-profile variability is very complex: simultaneous variations occur on quite different time scales - about 7 years for the VLT variability; about 600 days for the LT variability; 200 days for the DAC-related variability; and 3 to 4 months for the "swaying'' variability - and all of them, excluding the LT variability, are of a recurrent character. The variations of each kind involve continuous changes in the number density over an extended, in radial and azimuthal direction, region of the wind. Surprisingly, variations of different kinds (i.e. of different time-scales) do not appear to be directly linked. Even when they operate in one and the same wind region (in velocity space) it is not obvious whether and how they interact. Mass-loss variations in a spherically-symmetric stellar wind do not seem to be capable of explaining the properties of the phenomena observed. The wind variability of P Cygni is qualitatively similar in several aspects to the variability of the B supergiant HD64760 implying a similar density structure of their winds.
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