Fundamental parameters of massive stars in multiple systems: The cases of HD17505A and HD206267A

Many massive stars are part of binary or higher multiplicity systems. The present work focusses on two higher multiplicity systems: HD17505A and HD206267A. Determining the fundamental parameters of the components of the inner binary of these systems is mandatory to quantify the impact of binary or triple interactions on their evolution. We analysed high-resolution optical spectra to determine new orbital solutions of the inner binary systems. After subtracting the spectrum of the tertiary component, a spectral disentangling code was applied to reconstruct the individual spectra of the primary and secondary. We then analysed these spectra with the non-LTE model atmosphere code CMFGEN to establish the stellar parameters and the CNO abundances of these stars. The inner binaries of these systems have eccentric orbits with e ~ 0.13 despite their relatively short orbital periods of 8.6 and 3.7 days for HD17505Aa and HD206267Aa, respectively. Slight modifications of the CNO abundances are found in both components of each system. The components of HD17505Aa are both well inside their Roche lobe, whilst the primary of HD206267Aa nearly fills its Roche lobe around periastron passage. Whilst the rotation of the primary of HD206267Aa is in pseudo-synchronization with the orbital motion, the secondary displays a rotation rate that is higher. The CNO abundances and properties of HD17505Aa can be explained by single star evolutionary models accounting for the effects of rotation, suggesting that this system has not yet experienced binary interaction. The properties of HD206267Aa suggest that some intermittent binary interaction might have taken place during periastron passages, but is apparently not operating anymore.Comment: Accepted for publication in A&

Observational signatures of past mass-exchange episodes in massive binaries: The case of LSS 3074

The role of mass and momentum exchanges in close massive binaries is very important in the subsequent evolution of the components. Such exchanges produce several observational signatures such as asynchronous rotation and altered chemical compositions, that remain after the stars detach again. We investigated these effects for the close O-star binary LSS 3074 (O4 f + O6-7 :(f):), which is a good candidate for a past Roche lobe overflow (RLOF) episode because of its very short orbital period, P = 2.185 days, and the luminosity classes of both components. We determined a new orbital solution for the system. We studied the photometric light curves to determine the inclination of the orbit and Roche lobe filling factors of both stars. Using phase-resolved spectroscopy, we performed the disentangling of the optical spectra of the two stars. We then analysed the reconstructed primary and secondary spectra with the CMFGEN model atmosphere code to determine stellar parameters, such as the effective temperatures and surface gravities, and to constrain the chemical composition of the components. We confirm the apparent low stellar masses and radii reported in previous studies. We also find a strong overabundance in nitrogen and a strong carbon and oxygen depletion in both primary and secondary atmospheres, together with a strong enrichment in helium of the primary star. We propose several possible evolutionary pathways through a RLOF process to explain the current parameters of the system. We confirm that the system is apparently in overcontact configuration and has lost a significant portion of its mass to its surroundings. We suggest that some of the discrepancies between the spectroscopic and photometric properties of LSS 3074 could stem from the impact of a strong radiation pressure of the primary

Observational signatures of past mass-exchange episodes in massive binaries: The case of HD 149 404

Context. Mass and momentum exchanges in close massive binaries play an important role in their evolution, and produce several observational signatures such as asynchronous rotation and altered chemical compositions, that remain after the stars detach again. Aims: We investigated these effects for the detached massive O-star binary HD 149 404 (O7.5 If + ON9.7 I, P = 9.81 days), which is thought to have experienced a past episode of case A Roche-lobe overflow (RLOF). Methods: Using phase-resolved spectroscopy, we performed the disentangling of the optical spectra of the two stars. The reconstructed primary and secondary spectra were then analysed with the CMFGEN model atmosphere code to determine stellar parameters, such as the effective temperatures and surface gravities, and to constrain the chemical composition of the components. We complemented the optical study with the study of IUE spectra, which we compare to the synthetic binary spectra. The properties of the stars were compared to evolutionary models. Results: We confirmed a strong overabundance in nitrogen ([N/C] ~ 150[N/C][SUB]⊙[/SUB]) for the secondary and a slight nitrogen overabundance ([N/C] ~ 5[N/C][SUB]⊙[/SUB]) for the primary star. Comparing the two stars, we found evidence for asynchronous rotation, with a rotational period ratio of 0.50 ± 0.11. Conclusions: The hypothesis of a past case A RLOF interaction in HD 149 404 is most plausible to explain its chemical abundances and rotational asynchronicity. Some of the observed properties, such as the abundance pattern, are clearly a challenge for current case A binary evolution models, however.ARC - Actions de recherche concertées; Etoiles massive

Terminological challenges in the translation of science documentaries: a case-study

This article aims to describe some of the main terminological problems audiovisual translators have to face when dealing with the translation of science documentaries, specifically in the English-Catalan combination. The first section of the article presents some theoretical concepts which underlie this research and which are taken, for the most part, from Cabré's Communicative Theory of Terminology. Then, specific terminological problems audiovisual translators have to solve are described using the data provided by a corpus of four science documentaries lasting approximately 50 minutes each. These challenges include identifying a term, understanding a term, finding the right equivalent, dealing with the absence of an adequate equivalent, solving denominative variations, choosing between in vivo and in vitro terminology, and overcoming mistranscriptions

Fundamental parameters of massive stars in multiple systems: The cases of HD 17505A and HD 206267A

© 2018 ESO. Context. Many massive stars are part of binary or higher multiplicity systems. The present work focusses on two higher multiplicity systems: HD 17505A and HD 206267A. Aims. Determining the fundamental parameters of the components of the inner binary of these systems is mandatory to quantify the impact of binary or triple interactions on their evolution. Methods. We analysed high-resolution optical spectra to determine new orbital solutions of the inner binary systems. After subtracting the spectrum of the tertiary component, a spectral disentangling code was applied to reconstruct the individual spectra of the primary and secondary. We then analysed these spectra with the non-LTE model atmosphere code CMFGEN to establish the stellar parameters and the CNO abundances of these stars. Results. The inner binaries of these systems have eccentric orbits with e ∼ 0.13 despite their relatively short orbital periods of 8.6 and 3.7 days for HD 17505Aa and HD 206267Aa, respectively. Slight modifications of the CNO abundances are found in both components of each system. The components of HD 17505Aa are both well inside their Roche lobe, whilst the primary of HD 206267Aa nearly fills its Roche lobe around periastron passage. Whilst the rotation of the primary of HD 206267Aa is in pseudo-synchronization with the orbital motion, the secondary displays a rotation rate that is higher. Conclusions. The CNO abundances and properties of HD 17505Aa can be explained by single star evolutionary models accounting for the effects of rotation, suggesting that this system has not yet experienced binary interaction. The properties of HD 206267Aa suggest that some intermittent binary interaction might have taken place during periastron passages, but is apparently not operating anymore.keywords: stars: early-type, binaries: spectroscopic, stars: fundamental parameters, stars: massive, stars: individual: HD17505, stars: individual: HD206267, Astrophysics - Solar and Stellar Astrophysics eid: A60 archiveprefix: arXiv primaryclass: astro-ph.SR adsurl: https://ui.adsabs.harvard.edu/abs/2018A&A...614A..60R adsnote: Provided by the SAO/NASA Astrophysics Data Systemstatus: publishe

BRITE photometry of the massive post-RLOF system HD149 404

Context. HD 149 404 is an evolved non-eclipsing O-star binary that has previously undergone a Roche lobe overflow interaction. Aims: Understanding some key properties of the system requires a determination of the orbital inclination and of the dimensions of the components. Methods: The BRITE-Heweliusz satellite was used to collect photometric data of HD 149 404. Additional photometry was retrieved from the SMEI archive. These data were analysed using a suite of period search tools. The orbital part of the lightcurve was modelled with the nightfall binary star code. The Gaia-DR2 parallax of HD 149 404 was used to provide additional constraints. Results: The periodograms reveal a clear orbital modulation of the lightcurve with a peak-to-peak amplitude near 0.04 mag. The remaining non-orbital part of the variability is consistent with red noise. The lightcurve folded with the orbital period reveals ellipsoidal variations, but no eclipses. The minimum when the secondary star is in inferior conjunction is deeper than the other minimum due to mutual reflection effects between the stars. Combined with the Gaia-DR2 parallaxes, the photometric data indicate an orbital inclination in the range of 23°-31° and a Roche lobe filling factor of the secondary larger than or equal to 0.96. Conclusions: The luminosity of the primary star is consistent with its present-day mass, whereas the more evolved secondary appears overluminous for its mass. We confirm that the primary's rotation period is about half the orbital period. Both features most probably stem from the past Roche lobe overflow episode. Based on data collected by the BRITE-Constellation satellite mission, designed, built, launched, operated and supported by the Austrian Research Promotion Agency (FFG), the University of Vienna, the Technical University of Graz, the University of Innsbruck, the Canadian Space Agency (CSA), the University of Toronto Institute for Aerospace Studies (UTIAS), the Foundation for Polish Science & Technology (FNiTP MNiSW), and the National Science Centre (NCN)

Catalogue of particle-accelerating colliding-wind binaries

Massive systems made of two or more stars are known to be the site for interesting physical processes -- including at least in some cases -- particle acceleration. Over the past decade, this topic motivated a particular effort to unveil the properties of these systems and characterize the circumstances responsible for the acceleration of particles and the potential role of pre-supernova massive stars in the production of high energy particles in our Galaxy. Although previous studies on this topic were mostly devoted to processes in general, or to a few individual objects in particular, a unified target-oriented census of particle-accelerating colliding-wind binaries (hereafter PACWBs) does not exist yet. This paper aims at making a general and unified census of these systems, emphasizing their main properties. A general discussion includes energetic considerations along with wind properties in relation with non-thermal emission processes that are likely at work in colliding-wind binaries. Finally, some guidelines for future observational and theoretical studies are drawn

Mesozoic sedimentary cover sequences of the Congo Basin in the Kasai region, Democratic Republic of Congo

The Congo Basin represents one of the largest and least studied continental sedimentary basins in the world. The stratigraphy of cover sequences across the basin is poorly resolved and a somewhat simple stratigraphy has generally been applied with gross subdivision of the Mesozoic-Cenozoic cover sequences into a number weakly correlated units. Although these subdivisions are useful for broad, regional-scale correlations, investigation of drill cores and outcrop in the shallow, southern Kasai part of the basin, from Tshikapa to Kabinda, reveals considerable facies, provenance and thickness variations, suggesting a more complex depositional and stratigraphic history than previously recognized. This study now permits the subdivision of the sedimentary cover in the Kasai portion of the Congo Basin into five distinct depositional sequences consisting of (1) P1: Permo-Carboniferous glacio-lacustrine deposits correlative to the Lukuga Group; (2) J1: Jurassic-age arid to semi-arid laminated shales and siltstones and aeolian sandstones, interpreted as ephemeral lake and sand dune sequences with interspersed loess deposits and rare fluvial channel sequences (considered part of the historic Lualaba-Lubilash Supergroup—the lacustrine facies likely correlates with the Stanleyville Group, DRC and the Continental Intercalar Group, Angola); (3) C1 & C2: Lower Cretaceous locally heavy mineral-rich fluvial sandstone deposits and variably present basal conglomerate (correlated to the Loia Group, DRC and the Calonda Formation, Angola); (4) C3 & C4: Upper Cretaceous conglomerates of alluvial fan origin that grade upward into laminated shales and siltstones or well-sorted and rounded, fined grained sandstones representative of a semi-arid to arid depositional setting dominated by ephemeral lakes and small aeolian dunes, (equated to the Kwango Group, DRC and Angola) and (5) T1: fluvial, aeolian and lacustrine sediments of Paleogene age (correlated with portions of the Kalahari Group). The results convincingly suggest that this part of the Congo Basin is more structurally complex than previously appreciated, with multiple fault-bounded basement highs and depocenters that strongly influenced regional sedimentation patterns. Prolonged and sporadic displacement appears to have taken place along these faults, leading to heavily bisected basin morphology with uneven thickness and depth distributions between sequences. The deposition of Cretaceous sequences was coeval with two episodes of kimberlite emplacement, the first at ~120–130 Ma in northern Angola, and the second at ~70–80 Ma in the DRC, with gravel horizons within the Cretaceous fluvial successions (C1 and C3) known for their alluvial diamond concentration. The models developed provide a regional context for evaluation of alluvial diamond source areas and prospectivity