Modelling of the B-type binaries CW Cephei and U Ophiuchi

Johnston, C.; Pavlovski, K.; Tkachenko, A.

doi:10.1051/0004-6361/201935235

Cited by 43 publications

(37 citation statements)

References 108 publications

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“…We note that without smaller uncertainties on the parameters of the primary, we are not able to constrain the impact of internal chemical mixing on the evolution of this star. Additionally, without proper characterization of the secondary via detection of its RV variations, we are not able to perform isochronecloud fitting as introduced by Johnston et al (2019b) and applied by Tkachenko et al (2020).…”

Section: Discussionmentioning

confidence: 99%

Characterization of the variability in the O+B eclipsing binary HD 165246

Johnston

Aimar

Abdul-Masih

et al. 2021

Monthly Notices of the Royal Astronomical Society

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O-stars are known to experience a wide range of variability mechanisms originating at both their surface and their near-core regions. Characterization and understanding of this variability and its potential causes are integral for evolutionary calculations. We use a new extensive high-resolution spectroscopic data set to characterize the variability observed in both the spectroscopic and space-based photometric observations of the O+B eclipsing binary HD 165246. We present an updated atmospheric and binary solution for the primary component, involving a high level of microturbulence ($13_{-1.3}^{+1.0}\,$km s−1) and a mass of $M_1=23.7_{-1.4}^{+1.1}$ M⊙, placing it in a sparsely explored region of the Hertzsprung-Russell diagram. Furthermore, we deduce a rotational frequency of 0.690 ± 0.003 d−1 from the combined photometric and line-profile variability, implying that the primary rotates at 40% of its critical Keplerian rotation rate. We discuss the potential explanations for the overall variability observed in this massive binary, and discuss its evolutionary context.

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Section: Discussionmentioning

confidence: 99%

Characterization of the variability in the O+B eclipsing binary HD 165246

Johnston

Aimar

Abdul-Masih

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…However, a careful inspection of the literature and available data reveals that they are actually no classical Be stars. For example CW Cep, listed as classical Be star of spectral type B1Vve in BeSS was found to be a 2.7 d-period B+B binary system with stationary Hα emission from circumbinary material (Johnston et al 2019). We discuss these objects in more detail in Appendix B.3.…”

Section: Analysis Of the Available Literaturementioning

confidence: 99%

Investigating the lack of main-sequence companions to massive Be stars

Bodensteiner

Shenar

Sana

2020

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Context. About 20% of all B-type stars are classical Be stars – stars whose spectra imply the presence of a circumstellar decretion disk. The disk phenomenon is strongly correlated with rapid rotation, the origin of which remains unclear. It may be rooted in single- or binary-star evolution. In the framework of the binary channel, the initially more massive star transfers mass and angular momentum to the original secondary, which becomes a Be star. The system then evolves into a Be binary with a post-main-sequence companion, which, depending on the companion mass, may later be disrupted in a supernova event. Hence, if the binary channel dominates the formation of Be stars, one may expect a strong lack of close Be binaries with main sequence (MS) companions. Aims. We want to test the prediction of the binary channel. Through an extensive, star-by-star review of the literature of a magnitude-limited sample of Galactic early-type Be stars, we investigate whether Be binaries with MS companions are known to exist. Methods. Our sample is constructed from the BeSS database and cross-matched with all available literature on the individual stars. Archival and amateur spectra are used to verify the existing literature when conflicting reports are found. Results. Out of an initial list of 505 Be stars, we compile a final sample of 287 Galactic Be stars earlier than B1.5 with V ≤ 12 mag. Out of those, 13 objects were reported as Be binaries with known post-MS companions (i.e., compact objects or helium stars) and 11 as binaries with unknown, uncertain or debated companions. We find no confirmed reports of Be binaries with MS companions. For the remaining 263 targets, no significant reports of multiplicity exist in the literature, implying that they are either Be binaries with faint companions, or truly single. Conclusions. The clear lack of reported MS companions to Be stars, which stands in contrast to the high number of detected B+B MS binaries, strongly supports the hypothesis that early-type Be stars are binary interaction products that spun up after mass and angular momentum transfer from a companion star. Taken at face value, our results may suggest that a large majority of the early-type Be stars have formed through binary mass-transfer.

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“…It is known that many massive stars are members of multiple systems, which interact over the course of their lifetimes, so theoretical uncertainties are further compounded by the effects of binarity and mass transfer (Podsiadlowski et al, 1992;Sana et al, 2012;de Mink et al, 2013;Duchêne and Kraus, 2013;Moe and Di Stefano, 2017). However, despite the complexities associated with rotation, metallicity, mass loss and magnetic fields, massive stars in multiple systems have proven extremely useful in probing and mitigating model parameter uncertainties (Guinan et al, 2000;Hilditch et al, 2005;Torres et al, 2010;Tkachenko et al, 2014Tkachenko et al, , 2016Almeida et al, 2015;Abdul-Masih et al, 2019;Johnston et al, 2019;Mahy et al, 2020a,b). This is primarily because binary studies have the potential to provide masses and radii from the stars' relative orbital motion around a common center of mass.…”

Section: Introductionmentioning

confidence: 99%

Asteroseismology of High-Mass Stars: New Insights of Stellar Interiors With Space Telescopes

Bowman

2020

Front. Astron. Space Sci.

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Massive stars are important metal factories in the Universe. They have short and energetic lives, and many of them inevitably explode as a supernova and become a neutron star or black hole. In turn, the formation, evolution and explosive deaths of massive stars impact the surrounding interstellar medium and shape the evolution of their host galaxies. Yet the chemical and dynamical evolution of a massive star, including the chemical yield of the ultimate supernova and the remnant mass of the compact object, strongly depend on the interior physics of the progenitor star. We currently lack empirically calibrated prescriptions for various physical processes at work within massive stars, but this is now being remedied by asteroseismology. The study of stellar structure and evolution using stellar oscillations-asteroseismology-has undergone a revolution in the last two decades thanks to high-precision time series photometry from space telescopes. In particular, the long-term light curves provided by the MOST, CoRoT, BRITE, Kepler/K2, and TESS missions provided invaluable data sets in terms of photometric precision, duration and frequency resolution to successfully apply asteroseismology to massive stars and probe their interior physics. The observation and subsequent modeling of stellar pulsations in massive stars has revealed key missing ingredients in stellar structure and evolution models of these stars. Thus, asteroseismology has opened a new window into calibrating stellar physics within a highly degenerate part of the Hertzsprung-Russell diagram. In this review, I provide a historical overview of the progress made using ground-based and early space missions, and discuss more recent advances and breakthroughs in our understanding of massive star interiors by means of asteroseismology with modern space telescopes.

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Modelling of the B-type binaries CW Cephei and U Ophiuchi

Cited by 43 publications

References 108 publications

Characterization of the variability in the O+B eclipsing binary HD 165246

Characterization of the variability in the O+B eclipsing binary HD 165246

Investigating the lack of main-sequence companions to massive Be stars

Asteroseismology of High-Mass Stars: New Insights of Stellar Interiors With Space Telescopes

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