The Tarantula Massive Binary Monitoring

Mahy, L.; Almeida, L. A.; Sana, H.; Clark, J. S.; Koter, A. de; Mink, S. E. de; Evans, C. J.; Grin, N. J.; Langer, N.; Moffat, A. F. J.; Schneider, F. R. N.; Shenar, T.; Tramper, F.

doi:10.1051/0004-6361/201936152

Cited by 39 publications

(28 citation statements)

References 44 publications

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“…From the observed contact systems, VFTS 217 is closest to this regime. However, Mahy et al (2020b) find that neither of the components of this system is overluminous. On the other hand, (Abdul-Masih et al prep) show that likely both components, but certainly the less massive one, of the systems V382 Cyg, and OGLE 108086 are overluminous.…”

Section: Discussionmentioning

confidence: 78%

Detailed evolutionary models of massive contact binaries – I. Model grids and synthetic populations for the Magellanic Clouds

Menon

Langer

Mink

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The majority of close massive binary stars with initial periods of a few days experience a contact phase, in which both stars overflow their Roche lobes simultaneously. We perform the first dedicated study of the evolution of massive contact binaries and provide a comprehensive prediction of their observed properties. We compute 2790 detailed binary models for the Large and Small Magellanic Clouds each, assuming mass transfer to be conservative. The initial parameter space for both grids span total masses from 20 to 80 M⊙ , orbital periods of 0.6 to 2 days and mass ratios of 0.6 to 1.0. We find that models that remain in contact over nuclear timescales evolve towards equal masses, echoing the mass ratios of their observed counterparts. Ultimately, the fate of our nuclear-timescale models is to merge on the main sequence. Our predicted period-mass ratio distributions of O-type contact binaries are similar for both galaxies, and we expect 10 such systems together in both Magellanic Clouds. While we can largely reproduce the observed distribution, we over-estimate the population of equal-mass contact binaries. This situation is somewhat remedied if we also account for binaries that are nearly in contact. Our theoretical distributions work particularly well for contact binaries with periods <2 days and total masses ⪅45 M⊙ . We expect stellar winds, non-conservative mass transfer and envelope inflation to have played a role in the formation of the more massive and longer-period contact binaries.

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Section: Discussionmentioning

confidence: 78%

Detailed evolutionary models of massive contact binaries – I. Model grids and synthetic populations for the Magellanic Clouds

Menon

Langer

Mink

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…The main reason for this discrepancy is the low inferred log g, which should be raised by about 0.25 dex for both stars, that is, slightly beyond the adopted uncertainty, to match the dynamical masses. The mass discrepancy problem (Herrero et al 1992) is still an open issue in massive-star spectroscopy, and while more recent studies (e.g., Mahy et al 2020) show that for stars above ∼35M , the discrepancy largely disappears, in this analysis, it is still present. The repeated normalization of the spectra before and after disentangling could be the root cause of this fact, as the reconstruction plots in Fig.…”

Section: Resultsmentioning

confidence: 60%

Resolving the dynamical mass tension of the massive binary 9 Sagittarii

Fabry

Hawcroft

Frost

et al. 2021

A&A

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Context. Direct dynamical mass measurements of stars with masses above 30 M⊙ are rare. This is the result of the low yield of the upper initial mass function and the limited number of such systems in eclipsing binaries. Long-period, double-lined spectroscopic binaries that are also resolved astrometrically offer an alternative to eclipsing binaries for obtaining absolute masses of stellar objects. 9 Sgr (HD 164794) is one such long-period, high-mass binary. Unfortunately, a large amount of tension exists between its total dynamical mass inferred spectroscopically from radial velocity measurements and that from astrometric data. Aims. Our goal is to resolve the mass tension of 9 Sgr that exists in literature, to characterize the fundamental parameters and surface abundances of both stars, and to determine the evolutionary status of the binary system, henceforth providing a reference calibration point to confront evolutionary models at high masses. Methods. We obtained the astrometric orbit from existing and new multi-epoch VLTI/PIONIER and VLTI/GRAVITY interferometric measurements. Using archival and new spectroscopy, we performed a grid-based spectral disentangling search to constrain the semi-amplitudes of the radial velocity curves. We computed atmospheric parameters and surface abundances by adjusting FASTWIND atmosphere models and we compared our results with evolutionary tracks computed with the Bonn Evolutionary Code (BEC). Results. Grid spectral disentangling of 9 Sgr supports the presence of a 53 M⊙ primary and a 39 M⊙ secondary, which is in excellent agreement with their observed spectral types. In combination with the size of the apparent orbit, this puts 9 Sgr at a distance of 1.31 ± 0.06 kpc. Our best-fit models reveal a large mass discrepancy between the dynamical and spectroscopic masses, which we attribute to artifacts from repeated spectral normalization before and after the disentangling process. Comparison with BEC evolutionary tracks shows the components of 9 Sgr are most likely coeval with an age of roughly 1 Myr. Conclusions. Our analysis clears up the contradiction between mass and orbital inclination estimates reported in previous studies. We detect the presence of significant CNO-processed material at the surface of the primary, suggesting enhanced internal mixing compared to currently implemented in the BEC models. The present measurements provide a high-quality high-mass anchor to validate stellar evolution models and to test the efficiency of internal mixing processes.

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“…In the near future, we hope to develop a comprehensive model database of remnants and their predicted observational outcomes for a range of events. Such a formalism would serve as a valuable theoretical counterpart to the increasing number of merger remnant products expected to be uncovered in future observational surveys (Sana et al 2013;Almeida et al 2017;Mahy et al 2020).…”

Section: Discussionmentioning

confidence: 99%

The Art of Modeling Stellar Mergers and the Case of the B[e] Supergiant R4 in the Small Magellanic Cloud

Everson

Schneider

et al. 2020

ApJ

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Most massive stars exchange mass with a companion, leading to evolution which is altered drastically from that expected of stars in isolation. Such systems result from unusual binary evolution pathways and can place stringent constraints on the physics of these interactions. We use the R4 binary system's B[e] supergiant, which has been postulated to be the product of a stellar merger, to guide our understanding of such outcomes by comparing observations of R4 to the results of simulating a merger with the 3D hydrodynamics code FLASH. Our approach tailors the simulation initial conditions to observed properties of R4 and implements realistic stellar profiles from the 1D stellar evolution code MESA onto the 3D grid, resolving the merger inspiral to within 0.02 R e. We map the merger remnant into MESA to track its evolution on the H-R diagram over a period of 10 4 yr. This generates a model for a B[e] supergiant with stellar properties, age, and nebula structure in qualitative agreement with those of the R4 system. Our calculations provide evidence to support the idea that R4ʼs B[e] supergiant was originally a member of a triple system in which the inner binary merged after its most massive member evolved off the main sequence, producing a new object of similar mass but significantly more luminosity than the A supergiant companion. The code framework presented in this paper, which was constructed to model tidal encounters, can be used to generate accurate models of a wide variety of merger stellar remnants.

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The Tarantula Massive Binary Monitoring

Cited by 39 publications

References 44 publications

Detailed evolutionary models of massive contact binaries – I. Model grids and synthetic populations for the Magellanic Clouds

Detailed evolutionary models of massive contact binaries – I. Model grids and synthetic populations for the Magellanic Clouds

Resolving the dynamical mass tension of the massive binary 9 Sagittarii

The Art of Modeling Stellar Mergers and the Case of the B[e] Supergiant R4 in the Small Magellanic Cloud

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