J/A+A/640/A36 OB stars TESS phot. & high-resolution spectroscopy (Bowman+, 2020)
Photometric detection of internal gravity waves in upper main-sequence stars.
II. Combined TESS photometry and high-resolution spectroscopy.
Bowman D.M., Burssens S., Simon-diaz S., Edelmann P.V.F., Rogers T.M.,
Horst L., Ropke F.K., Aerts C.
<Astron. Astrophys., 640, A36 (2020)>
=2020A&A...640A..36B 2020A&A...640A..36B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, OB ; Asteroseismology ; Spectroscopy
Keywords: asteroseismology - stars: early-type - stars: oscillations -
stars: evolution - stars: rotation - stars: fundamental parameters
Abstract:
Massive stars are predicted to excite internal gravity waves (IGWs) by
turbulent core convection and from turbulent pressure fluctuations in
their near-surface layers. These IGWs are extremely efficient at
transporting angular momentum and chemical species within stellar
interiors, but they remain largely unconstrained observationally.
We aim to characterise the photometric detection of IGWs across a
large number of O and early-B stars in the Hertzsprung-Russell
diagram, and explain the ubiquitous detection of stochastic
variability in the photospheres of massive stars.
We combined high-precision time-series photometry from the NASA
Transiting Exoplanet Survey Satellite with high-resolution
ground-based spectroscopy of 70 stars with spectral types O and B to
probe the relationship between the photometric signatures of IGWs and
parameters such as spectroscopic mass, luminosity, and
macroturbulence.
A relationship is found between the location of a star in the
spectroscopic Hertzsprung-Russell diagram and the amplitudes and
frequencies of stochastic photometric variability in the light curves
of massive stars. Furthermore, the properties of the stochastic
variability are statistically correlated with macroturbulent velocity
broadening in the spectral lines of massive stars.
The common ensemble morphology for the stochastic low-frequency
variability detected in space photometry and its relationship to
macroturbulence is strong evidence for IGWs in massive stars, since
these types of waves are unique in providing the dominant tangential
velocity field required to explain the observed spectroscopy.
Description:
The spectroscopic parameters of our sample are provided by Burssens et
al. (2020A&A...639A..81B 2020A&A...639A..81B , Cat. J/A+A/639/A81) and include the
effective temperature, Teff, spectroscopic luminosity,
log10(Ls/Ls☉), projected surface rotational velocity,
vsini, and macroturbulent broadening, vmacro. These were derived
from high-resolution spectra assembled by the IACOB (Simon-Diaz et
al., 2011, Bull. Soc. R. Sci. Liege, 80, 514; 2015, in Highlights of
Spanish Astrophysics VIII, eds. A. J. Cenarro, F. Figueras, C.
Hernandez-Monteagudo, J. Trujillo Bueno, & L. Valdivielso, 576) and
OWN (Barba et al. 2010, Rev. Mex. Astron. Astrofis. Conf. Ser., 38,
30; 2014, Rev. Mex. Astron. Astrofis. Conf. Ser., 44, 148; 2017, in
The Lives and Death-Throes of Massive Stars, eds. J. J. Eldridge, J.
C. Bray, L. A. S. McClelland, & L. Xiao, IAU Symp., 329, 89) surveys.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 57 70 Parameters of OB stars studied in this work
tablea2.dat 83 70 Optimised parameters for the morphology of
low-frequency variability (cf. Eq. (2)) using
a Bayesian MCMC fitting method
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See also:
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
J/A+A/639/A81 : Variability of OB stars (Burssens+, 2020)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1 I1 --- Cat [1/9] Category (G1)
3- 13 A11 --- Name Common name
15- 23 I9 --- TIC TIC number
25- 39 A15 --- SpType Spectral type
41- 44 F4.2 [K] logTeff Effective temperature
(typical uncertainty 0.03dex)
46- 49 F4.2 [Sun] logLs Spectroscopic luminosity (where Ls=Teff4/g)
(typical uncertainty 0.15dex)
51- 53 I3 km/s vsini Projected surface rotational velocity (1)
55- 57 I3 km/s vmacro ? Macroturbulent broadening (1)
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Note (1): taken from Burssens et al. (2020A&A...639A..81B 2020A&A...639A..81B, Cat. J/A+A/639/A81).
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1 I1 --- Cat [1/9] Category (G1)
3- 13 A11 --- Name Common name
15- 23 I9 -- TIC TIC number
25- 32 F8.3 umag alpha0 Amplitude at a frequency of zero
34- 38 F5.3 umag e_alpha0 rms uncertainty on alpha0
40- 46 F7.5 d-1 nuchar Characteristic frequency
48- 54 F7.5 d-1 e_nuchar rms uncertainty on nuchar
56- 62 F7.5 --- gamma logarithmic amplitude gradient
64- 70 F7.5 --- e_gamma rms uncertainty on gamma
72- 77 F6.3 umag Cw Frequency-independent noise term
79- 83 F5.3 umag e_Cw rms uncertainty on Cw
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Global notes:
Note (G1): Category as follows:
1 = O dwarf stars
2 = O subgiant stars
3 = O giant stars
4 = O bright giant and supergiant stars
5 = B dwarf stars
6 = B subgiant stars
7 = B giant stars
8 = B bright giant and supergiant stars
9 = Peculiar stars
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History:
From electronic version of the journal
References:
Bowman et al., Paper I 2019A&A...621A.135B 2019A&A...621A.135B
(End) Patricia Vannier [CDS] 09-Oct-2020