Interplay between pulsations and mass loss in the blue supergiant 55 Cygnus = HD 198 478

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F15%3A00449317" target="_blank" >RIV/67985815:_____/15:00449317 - isvavai.cz</a>
Alternative codes found
RIV/00216208:11320/15:10379328
Result on the web
<a href="http://dx.doi.org/10.1051/0004-6361/201425383" target="_blank" >http://dx.doi.org/10.1051/0004-6361/201425383</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1051/0004-6361/201425383" target="_blank" >10.1051/0004-6361/201425383</a>

Result language
angličtina
Original language name
Interplay between pulsations and mass loss in the blue supergiant 55 Cygnus = HD 198 478
Original language description
To investigate a possible interplay between pulsations and mass-loss, we carried out an observational campaign of the supergiant 55 Cyg over a period of five years to search for photospheric activity and cyclic mass-loss variability in the stellar wind. We modeled the H, He I, Si II, and Si III lines using the nonlocal thermal equilibrium atmosphere code FASTWIND and derived the photospheric and wind parameters. In addition, we searched for variability in the intensity and radial velocity of photospheric lines and performed a moment analysis of the line profiles to derive frequencies and amplitudes of the variations. The Ha line varies with time in both intensity and shape, displaying various types of profiles: P Cygni, pure emission, almost complete absence, and double or multiple peaked. The star undergoes episodes of variable mass-loss rates that change by a factor of 1.7-2 on different timescales. We also observe changes in the ionization rate of Si II and determine a multiperiodic oscillation in the He I absorption lines, with periods ranging from a few hours to 22.5 days. We interpret the photospheric line variations in terms of oscillations in p-, g-, and strange modes. We suggest that these pulsations can lead to phases of enhanced mass loss.
Czech name
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Czech description
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Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10308 - Astronomy (including astrophysics,space science)

Project
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Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year
2015
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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