J/A+A/692/A245 Hot massive stars parameters (Serebriakova+, 2024)
The ESO UVES/FEROS Large Programs of TESS OB pulsators.
II. The physical origin of macroturbulence.
Serebriakova N., Tkachenko A., Aerts C.
<Astron. Astrophys. 692, A245 (2024)>
=2024A&A...692A.245S 2024A&A...692A.245S (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Magellanic Clouds ; Stars, early-type ;
Effective temperatures ; Rotational velocities
Keywords: stars: fundamental parameters - stars: massive - stars: early-type -
stars: oscillations - techniques: spectroscopic
Abstract:
Spectral lines of hot massive stars are known to exhibit large excess
broadening in addition to rotational broadening. This excess
broadening is often attributed to macroturbulence, whose physical
origin is a matter of active debate in the stellar astrophysics
community.
We aim to shed light on the physical origin of macroturbulent line
broadening by looking into the statistical properties of a large
sample of O- and B-type stars both in the Galaxy and the Large
Magellanic Cloud (LMC).
We deliver newly measured macroturbulent velocities for 86 stars from
the Galaxy in a consistent manner with 126 stars from the LMC. We
composed a total sample of 594 stars with measured macroturbulent
velocities by complementing our sample with archival data for the
Galactic O- and B-type stars in order to gain better coverage of the
parameter space. Furthermore, we computed an extensive grid of MESA
models to compare, in a statistical manner, the predicted interior
properties of stars (such as convection and wave propagation) with the
inference of macroturbulent velocities from high-resolution
spectroscopic observations.
We find evidence for subsurface convective zones that formed in the
iron opacity bump (FeCZ) being connected to observed macroturbulent
velocities in hot massive stars. Additionally, we find the presence of
two principally different regimes where, depending on the initial
stellar mass, different mechanisms may be responsible for the observed
excess line broadening.
Stars with initial masses above 30M☉ exhibit macroturbulent
velocities that are in line with FeCZ properties, as indicated by the
trends in both observations and models. For stars below 12M☉,
alternative mechanisms are needed to explain macroturbulent
broadening, such as internal gravity waves (IGWs). Finally, in the
intermediate range between 12 and 30M☉, IGWs tunnelling through
subsurface convective layers combined with the presence of FeCZ-driven
convection suggests that both processes could contribute to the
observed macroturbulent velocities. This intermediate regime presents
a region where the interplay between these two (or more) mechanisms
remains to be fully understood.
Description:
This catalog contains data (atmospheric parameters and line
broadening) from a study of macroturbulent velocities in hot massive
stars. The sample includes 210 stars, consisting of 124 stars from the
LMC and 86 stars from the Galaxy.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 92 210 *Relevant parameters of the sample
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Note on table.dat: Data for the LMC stars are adopted from Serebriakova et al.,
2023A&A...676A..85S 2023A&A...676A..85S (tables published in the paper, not deposited in CDS).
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See also:
J/A+A/665/A36 : FEROS spectroscopy of B-type stars (Gebruers+, 2022)
Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- Name Object name
25- 29 I5 K Teff Effective temperature (rounded) (1)
31- 34 I4 K e_Teff Error in effective temperature (1)
36- 39 F4.2 [cm/s2] logg Log10 Surface gravity (1)
41- 44 F4.2 [cm/s2] e_logg Error in logg (1)
46- 50 F5.1 km/s Vsini-sp Projected rotational velocity (1) (2)
52- 55 F4.1 km/s e_Vsini-sp Error in Vsini-sp (1)
57- 61 F5.1 km/s Vsini-fourier ?=- Projected rotational velocity
(Fourier) (3)
63- 66 F4.1 km/s e_Vsini-fourier ?=- Error in Vsini-fourier
68- 72 F5.1 km/s Vmacro ?=- Macroturbulent velocity
74- 78 F5.1 km/s e_Vmacro ?=- Error in Vmacro
80- 83 F4.2 [K4/g] Ls Log10 Spectroscopic luminosity Teff^4/g
85- 88 F4.2 [K4/g] e_Ls Error in Ls
90- 92 A3 --- Samp Sample (4)
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Note (1): Teff, logg and Vsini_sp for the 86 Galactic stars are adopted
from Gebruers et al., 2022A&A...665A..36G 2022A&A...665A..36G, Cat. J/A+A/665/A36.
Note (2): Vsini-sp is the projected rotational velocity derived while fitting
spectra to determine atmospheric parameters.
Note (3): Vsini-fourier is the projected rotational velocity derived from the
position of the first zero in the Fourier transform of line profiles.
Note (4): Sample as follows:
S23 = subsample from Serebriakova et al., 2023A&A...676A..85S 2023A&A...676A..85S
G22 = subsample of Gebruers et al., 2022A&A...665A..36G 2022A&A...665A..36G, Cat. J/A+A/665/A36,
with newly measured Vmacro and Vsini_fourier values. See our paper for details.
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Acknowledgements:
Nadya Serebriakova, nadya.serebriakova(at)kuleuven.be
References:
Serebriakova et al., Paper I 2023A&A...676A..85S 2023A&A...676A..85S
(End) Patricia Vannier [CDS] 27-Oct-2024