000006158 001__ 6158
000006158 005__ 20230123210245.0
000006158 0247_ $$2DOI$$a10.1051/0004-6361/202243839
000006158 037__ $$aSCART-2023-0083
000006158 100__ $$aGebruers, Sarah
000006158 245__ $$aAnalysis of high-resolution FEROS spectroscopy for a sample of variable B-type stars assembled from TESS photometry
000006158 260__ $$c2022
000006158 520__ $$aContext. Spectroscopic data are necessary to break degeneracies in the asteroseismic modelling of the interior structure in high- and intermediate-mass stars. With the TESS mission, the number of bright intermediate-mass B-type stars with long photometric light curves that are suitable for detailed asteroseismic studies has increased substantially compared to the pre-TESS era.  Aims: We derive precise photospheric stellar parameters for a sample of 166 B-type stars with TESS light curves through a homogeneous spectroscopic analysis. The variability types of these sample stars are also classified based on all currently available TESS sectors, and they are ultimately prioritised according to their astrophysical potential.  Methods: We obtained high-resolution spectra for all 166 targets with the FEROS spectrograph in the context of a large program. The spectra were reduced with the CERES pipeline, which we adapted to improve the quality of the reduced spectra. These spectra were subsequently analysed with ZETA-PAYNE, a machine-learning-based spectrum analysis algorithm, to infer precise stellar labels for all stars in the sample. Furthermore, the least-squares deconvolution (LSD) method was employed to investigate spectral line profile variability (LPV) and isolate binary systems from presumably single stars.  Results: The LSD profile analysis identified 26 spectroscopic double-lined binaries; the remainder of the sample are 42 supergiants in the Large Magellanic Cloud galaxy and 98 Galactic stars, both with and without apparent LPV. For the Galactic single stars and single-lined spectroscopic binaries, we determine their five main surface parameters: effective temperature (Teff), surface gravity (log g), global metallicity ([M/H]), projected rotational velocity (v sin i), and microturbulent velocity (ξ) with average formal precisions of 70 K, 0.03 dex, 0.07 dex, 8 km s−1, and 0.7 km s−1, respectively. The average internal uncertainties we find for FEROS spectra with our spectrum analysis method are 430 K(Teff), 0.12 dex (log g), 0.13 dex ([M/H]), 12kms−1 (v sin i), and 2 kms−1 (ξ).  Conclusions: We find spectroscopic evidence that 8 of the 98 galactic single or SB1 variables are fast-rotating gravity-mode pulsators occurring in between the slowly pulsating B (SPB) stars and δ Scuti instability strips. The g-mode frequencies of these pulsators are shifted to relatively high frequency values due to their rotation, and their apparently too low Teff relative to the SPB instability region can in most cases be explained by the gravity darkening effect. We also discover 13 new HgMn stars in the Galactic sample of which only one is found in a spectroscopic binary, resulting in a biased and therefore unreliable low binary rate of only 8%.
000006158 594__ $$aNO
000006158 6531_ $$astars: fundamental parameters
000006158 6531_ $$astars: variables: general
000006158 6531_ $$astars: oscillations
000006158 6531_ $$aasteroseismology
000006158 6531_ $$atechniques: spectroscopic
000006158 6531_ $$aAstrophysics - Solar and Stellar Astrophysics
000006158 700__ $$aTkachenko, Andrew
000006158 700__ $$aBowman, Dominic M.
000006158 700__ $$aVan Reeth, Timothy
000006158 700__ $$a Burssens, Siemen
000006158 700__ $$aIJspeert, Luc
000006158 700__ $$aMahy, Laurent
000006158 700__ $$aStraumit, Ilya
000006158 700__ $$aXiang, Maosheng
000006158 700__ $$aRix, Hans-Walter 
000006158 700__ $$aAerts, Conny
000006158 773__ $$c17$$nA36$$pAstronomy & Astrophysics$$v665$$y2022
000006158 8560_ $$flaurent.mahy@ksb-orb.be
000006158 8564_ $$s2132933$$uhttp://publi2-as.oma.be/record/6158/files/Gebruers_2022_aa43839-22.pdf
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000006158 905__ $$apublished in
000006158 980__ $$aREFERD