Stochastic light variations in hot stars from wind instability:
finding photometric signatures and testing against the TESS
data

J 2021

Stochastic light variations in hot stars from wind instability: finding photometric signatures and testing against the TESS data

KRTIČKA, Jiří a Achim FELDMEIER

Základní údaje

Originální název

Stochastic light variations in hot stars from wind instability: finding photometric signatures and testing against the TESS data

Autoři

KRTIČKA, Jiří (203 Česká republika, garant, domácí) a Achim FELDMEIER

Vydání

Astronomy and Astrophysics, EDP Sciences, 2021, 0004-6361

Další údaje

Jazyk

angličtina

Typ výsledku

Článek v odborném periodiku

Obor

10308 Astronomy

Stát vydavatele

Francie

Utajení

není předmětem státního či obchodního tajemství

Odkazy

URL

Impakt faktor

Impact factor: 6.240

Kód RIV

RIV/00216224:14310/21:00118998

Organizační jednotka

Přírodovědecká fakulta

DOI

http://dx.doi.org/10.1051/0004-6361/202040148

UT WoS

000647070100001

Klíčová slova anglicky

stars: winds; outflows; stars: mass-loss; stars: early-type; hydrodynamics; instabilities; stars: variables: general

Štítky

rivok

Příznaky

Mezinárodní význam, Recenzováno

Změněno: 3. 6. 2021 09:26, Mgr. Marie Šípková, DiS.

Anotace

V originále

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.

Návaznosti

GA18-05665S, projekt VaV

Název: Ztráta hmoty v pozdních fázích vývoje hmotných hvězd

Investor: Grantová agentura ČR, Ztráta hmoty v pozdních fázích vývoje hmotných hvězd

Citovat

KRTIČKA, Jiří a Achim FELDMEIER. Stochastic light variations in hot stars from wind instability: finding photometric signatures and testing against the TESS data. Astronomy and Astrophysics. EDP Sciences, 2021, roč. 648, April, s. "A79", 9 s. ISSN 0004-6361. Dostupné z: https://dx.doi.org/10.1051/0004-6361/202040148.

@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, 2021, roč.~648, April, s.~''A79'', 9 s. ISSN~0004-6361. Dostupné z: https://dx.doi.org/10.1051/0004-6361/202040148.

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