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@article{1773338, author = {Krtička, Jiří and Feldmeier, Achim}, article_number = {April}, doi = {http://dx.doi.org/10.1051/0004-6361/202040148}, keywords = {stars: winds; outflows; stars: mass-loss; stars: early-type; hydrodynamics; instabilities; stars: variables: general}, language = {eng}, issn = {0004-6361}, journal = {Astronomy and Astrophysics}, title = {Stochastic light variations in hot stars from wind instability: finding photometric signatures and testing against the TESS data}, url = {https://doi.org/10.1051/0004-6361/202040148}, volume = {648}, year = {2021} }
TY - JOUR ID - 1773338 AU - Krtička, Jiří - Feldmeier, Achim PY - 2021 TI - Stochastic light variations in hot stars from wind instability: finding photometric signatures and testing against the TESS data JF - Astronomy and Astrophysics VL - 648 IS - April SP - "A79" EP - "A79" PB - EDP Sciences SN - 00046361 KW - stars: winds KW - outflows KW - stars: mass-loss KW - stars: early-type KW - hydrodynamics KW - instabilities KW - stars: variables: general UR - https://doi.org/10.1051/0004-6361/202040148 N2 - Context. Line-driven wind instability is expected to cause small-scale wind inhomogeneities, X-ray emission, and wind line profile variability. The instability can already develop around the sonic point if it is initiated close to the photosphere due to stochastic turbulent motions. In such cases, it may leave its imprint on the light curve as a result of wind blanketing.Aims. We study the photometric signatures of the line-driven wind instability.Methods. We used line-driven wind instability simulations to determine the wind variability close to the star. We applied two types of boundary perturbations: a sinusoidal one that enables us to study in detail the development of the instability and a stochastic one given by a Langevin process that provides a more realistic boundary perturbation. We estimated the photometric variability from the resulting mass-flux variations. The variability was simulated assuming that the wind consists of a large number of independent conical wind sectors. We compared the simulated light curves with TESS light curves of OB stars that show stochastic variability.Results. We find two typical signatures of line-driven wind instability in photometric data: a knee in the power spectrum of magnitude fluctuations, which appears due to engulfment of small-scale structure by larger structures, and a negative skewness of the distribution of fluctuations, which is the result of spatial dominance of rarefied regions. These features endure even when combining the light curves from independent wind sectors.Conclusions. The stochastic photometric variability of OB stars bears certain signatures of the line-driven wind instability. The distribution function of observed photometric data shows negative skewness and the power spectra of a fraction of light curves exhibit a knee. This can be explained as a result of the line-driven wind instability triggered by stochastic base perturbations. ER -
KRTIČKA, Jiří a Achim FELDMEIER. Stochastic light variations in hot stars from wind instability: finding photometric signatures and testing against the TESS data. \textit{Astronomy and Astrophysics}. EDP Sciences, roč.~648, April, s.~''A79'', 9 s. ISSN~0004-6361. doi:10.1051/0004-6361/202040148. 2021.
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