Searcharxiv⌕ Search

arXiv subjects

F. R. N. Schneider

Publications and source records attributed to F. R. N. Schneider.

At least 37 records · Page 2Linked to original sources
arXiv2024

A magnetic massive star has experienced a stellar merger

Massive stars (those larger than 8 solar masses at formation) have radiative envelopes that cannot sustain a dynamo, the mechanism that produces magnetic fields in lower-mass stars. Despite this, approximately 7\% of massive stars have observed magnetic fields, the origin of which is debated. We used multi-epoch interferometric and spectroscopic observations to characterize HD 148937, a binary system of two massive stars. We found that only one star is magnetic and that it appears younger than its companion. The system properties and a surrounding bipolar nebula can be reproduced with a model in which two stars merged (in a previous triple system) to produce the magnetic massive star. Our results provide observational evidence that magnetic fields form in at least some massive stars through stellar mergers.

astro-ph.SR↗
arXiv2024

Pre-supernova evolution and final fate of stellar mergers and accretors of binary mass transfer

The majority of massive stars are expected to exchange mass or merge with a companion during their lives. This immediately implies that most supernovae (SNe) are from such post-mass-exchange objects. Here, we explore how mass accretion and merging affect the pre-SN structures of stars and their final fates. We use the stellar evolution code MESA, infer the outcome of core-collapse using a neutrino-driven SN model, and apply a rapid-accretion model. Our models cover initial masses from 11 to 70 Msun and the accreted mass ranges from 10-200% of the initial mass. We find that mass accretion in particular onto post-main-sequence (post-MS) stars can lead to a long-lived blue supergiant (BSG) phase. In comparison to genuine single stars, post-MS accretors have small core-to-total mass ratios, regardless of whether they end their lives as BSGs or cool supergiants (CSGs), and they can have genuinely different pre-SN core structures. As in single and binary-stripped stars, we find black-hole (BH) formation for the same characteristic CO core masses M_CO of ~7 Msun and >13 Msun. In models with the largest mass accretion, the BH-formation landscape as a function of M_CO is shifted by about 0.5 Msun to lower masses. We find a tight relation between our neutron-star (NS) masses and the central entropy of the pre-SN models, suggesting a universal relation that is independent of the evolutionary history of stars. Post-MS accretors explode both as BSGs and CSGs, and we show how to understand their pre-SN locations in the Hertzsprung--Russell diagram. Some BSGs that avoid the luminous-blue-variable (LBV) regime are predicted to collapse into BHs of up to 50 Msun while others explode in supernovae and eject up to 40 Msun, greatly exceeding ejecta masses from single stars. These masses can be even higher at lower metallicities, and they may fall into the pair-instability-supernova mass gap. [abridged]

astro-ph.SR↗
arXiv2023

Going from 3D to 1D: A one-dimensional approach to common-envelope evolution

The common-envelope (CE) phase is a crucial stage in binary star evolution because the orbital separation can shrink drastically while ejecting the envelope of a giant star. Three-dimensional (3D) hydrodynamic simulations of CE evolution are indispensable to learning about the mechanisms that play a role during the CE phase. While these simulations offer great insight, they are computationally expensive. We propose a one-dimensional (1D) model to simulate the CE phase within the stellar evolution code $\texttt{MESA}$ by using a parametric drag force prescription for dynamical drag and adding the released orbital energy as heat into the envelope. We compute CE events of a $0.97\,\mathrm{M}_\odot$ asymptotic giant-branch star and a point mass companion with mass ratios of 0.25, 0.50, and 0.75, and compare them to 3D simulations of the same setup. The 1D CE model contains two free parameters, which we demonstrate are both needed to fit the spiral-in behavior and the fraction of ejected envelope mass of the 1D method to the 3D simulations. For mass ratios of 0.25 and 0.50, we find good-fitting 1D simulations, while for a mass ratio of 0.75, we do not find a satisfactory fit to the 3D simulation as some of the assumptions in the 1D method are no longer valid. In all our simulations, we find that the released recombination energy is important to accelerate the envelope and drive the ejection.

astro-ph.SR↗
arXiv2023

Convective-core overshooting and the final fate of massive stars

Massive stars can explode in powerful supernovae (SNe) forming neutron stars but they may also collapse directly into black holes (BHs). Understanding and predicting their final fate is increasingly important, e.g, in the context of gravitational-wave astronomy. The interior mixing of stars in general and convective boundary mixing remain some of the largest uncertainties in their evolution. Here, we investigate the influence of convective boundary mixing on the pre-SN structure and explosion properties of massive stars. Using the 1D stellar evolution code Mesa, we model single, non-rotating stars of solar metallicity with initial masses of $5-70\mathrm{M_\odot}$ and convective core step-overshooting of $0.05-0.50H_\mathrm{P}$. Stars are evolved until the onset of iron core collapse, and the pre-SN models are exploded using a parametric, semi-analytic SN code. We use the compactness parameter to describe the interior structure of stars at core collapse. Larger convective core overshooting shifts the location of the compactness peak by $1-2\mathrm{M_\odot}$ to higher $M_\mathrm{CO}$. As the luminosity of the pre-SN progenitor is determined by $M_\mathrm{CO}$, we predict BH formation for progenitors with luminosities $5.35<\log(L/\mathrm{L_\odot})<5.50$ and $\log(L/\mathrm{L_\odot})>5.80$. The luminosity range of BH formation agrees well with the observed luminosity of the red supergiant star N6946BH1 that disappeared without a bright SN and likely collapsed into a BH. While some of our models in the luminosity range $\log(L/\mathrm{L_\odot})=5.1-5.5$ indeed collapse to form BHs, this does not fully explain the lack of observed SN~IIP progenitors at these luminosities, ie the missing red-supergiant problem. Convective core overshooting affects the BH masses, the pre-SN location of stars in the Hertzsprung-Russell diagram, the plateau luminosity and duration of SN~IIP lightcurves.[Abridged]

astro-ph.SR↗
arXiv2023

Faint calcium-rich transient from the double-detonation of a $0.6\,M_\odot$ carbon-oxygen white dwarf star

We have computed a three-dimensional hydrodynamic simulation of the merger between a massive ($0.4\,M_\odot$) helium white dwarf (He WD) and a low-mass ($0.6\,M_\odot$) carbon-oxygen white dwarf (CO WD). Despite the low mass of the primary, the merger triggers a thermonuclear explosion as a result of a double detonation, producing a faint transient and leaving no remnant behind. This type of event could also take place during common-envelope mergers whenever the companion is a CO WD and the core of the giant star has a sufficiently large He mass. The spectra show strong Ca lines throughout the first few weeks after the explosion. The explosion only yields $<0.01\,M_\odot$ of $^{56}$Ni, resulting in a low-luminosity SN Ia-like lightcurve that resembles the Ca-rich transients within this broad class of objects, with a peak magnitude of $M_\mathrm{bol} \approx -15.7\,$mag and a rather slow decline rate of $Δm_{15}^\mathrm{bol}\approx 1.5\,$mag. Both, its lightcurve-shape and spectral appearance, resemble the appearance of Ca-rich transients, suggesting such mergers as a possible progenitor scenario for this class of events.

astro-ph.SR↗
arXiv2023

Scalable stellar evolution forecasting: Deep learning emulation vs. hierarchical nearest neighbor interpolation

Many astrophysical applications require efficient yet reliable forecasts of stellar evolution tracks. One example is population synthesis, which generates forward predictions of models for comparison with observations. The majority of state-of-the-art rapid population synthesis methods are based on analytic fitting formulae to stellar evolution tracks that are computationally cheap to sample statistically over a continuous parameter range. The computational costs of running detailed stellar evolution codes, such as MESA, over wide and densely sampled parameter grids are prohibitive, while stellar-age based interpolation in-between sparsely sampled grid points leads to intolerably large systematic prediction errors. In this work, we provide two solutions for automated interpolation methods that offer satisfactory trade-off points between cost-efficiency and accuracy. We construct a timescale-adapted evolutionary coordinate and use it in a two-step interpolation scheme that traces the evolution of stars from ZAMS all the way to the end of core helium burning while covering a mass range from ${0.65}$ to $300 \, \mathrm{M_\odot}$. The feedforward neural network regression model (first solution) that we train to predict stellar surface variables can make millions of predictions, sufficiently accurate over the entire parameter space, within tens of seconds on a 4-core CPU. The hierarchical nearest-neighbor interpolation algorithm (second solution) that we hard-code to the same end achieves even higher predictive accuracy, the same algorithm remains applicable to all stellar variables evolved over time, but it is two orders of magnitude slower. Our methodological framework is demonstrated to work on the MIST (Choi et al. 2016) data set. Finally, we discuss the prospective applications of these methods and provide guidelines for generalizing them to higher dimensional parameter spaces.

astro-ph.SR↗
arXiv2023

Self-consistent MHD simulation of jet launching in a neutron star - white dwarf merger

The merger of a white dwarf (WD) and a neutron star (NS) is a relatively common event that will produce an observable electromagnetic signal. Furthermore, the compactness of these stellar objects makes them an interesting candidate for gravitational wave (GW) astronomy, potentially being in the frequency range of LISA and other missions. To date, three-dimensional simulations of these mergers have not fully modelled the WD disruption, or have used lower resolutions and have not included magnetic fields even though they potentially shape the evolution of the merger remnant. In this work, we simulate the merger of a 1.4$M_\odot$ NS with a 1$M_\odot$ carbon oxygen WD in the magnetohydrodynamic moving mesh code \AREPO. We find that the disruption of the WD forms an accretion disk around the NS, and the subsequent accretion by the NS powers the launch of strongly magnetized, mildly relativistic jets perpendicular to the orbital plane. Although the exact properties of the jets could be altered by unresolved physics around the NS, the event could result in a transient with a larger luminosity than kilonovae. We discuss possible connections to fast blue optical transients (FBOTs) and long-duration gamma-ray bursts. We find that the frequency of GWs released during the merger is too high to be detectable by the LISA mission, but suitable for deci-hertz observatories such as LGWA, BBO or DECIGO.

astro-ph.HE↗
arXiv2023

The young massive SMC cluster NGC 330 seen by MUSE III. Stellar parameters and rotational velocities

The origin of initial rotation rates of stars, and how a star's surface rotational velocity changes during the evolution, either by internal angular momentum transport or due to interactions with a binary companion, remain open questions in stellar astrophysics. Here, we aim to derive the physical parameters and study the distribution of (projected) rotational velocities of B-type stars in the 35 Myr-old, massive cluster NGC 330 in the Small Magellanic Cloud. NGC 330 is in an age range where the number of post-interaction binaries is predicted to be high near the cluster turnoff (TO). We develop a simultaneous photometric and spectroscopic grid-fitting method adjusting atmosphere models on multi-band Hubble Space Telescope photometry and Multi Unit Spectroscopic Explorer spectroscopy. This allows us to homogeneously constrain the physical parameters of over 250 B and Be stars, brighter than mF814W = 18.8 mag. The rotational velocities of Be stars in NGC 330 are significantly higher than the ones of B stars. The rotational velocities vary as a function of the star's position in the color-magnitude diagram, qualitatively following predictions of binary population synthesis. A comparison to younger clusters shows that stars in NGC 330 rotate more rapidly on average. The rotational velocities of the 35 Myr old population in NGC 330 quantitatively agree with predictions for a stellar population that underwent significant binary interactions: the bulk of the B stars could be single stars or primaries in pre-interaction binaries. The rapidly spinning Be stars could be mass and angular momentum gainers in previous interactions, while those Be stars close to the TO may be spun-up single stars. The slowly rotating, apparently single stars above the TO could be merger products. The different vsini-characteristics of NGC 330 compared to younger populations can be understood in this framework.

astro-ph.SR↗
arXiv2022

The VLT-FLAMES Tarantula Survey: Observational evidence for two distinct populations of massive runaway stars in 30 Doradus

Two main scenarios have been proposed for origin of massive runaway stars -- dynamical ejection or release from a binary at the first core collapse -- but their relative contribution remains debated. Using two large spectroscopic campaigns towards massive stars in 30 Doradus, we aim to provide observational constraints on the properties of the O-type runaway population in the most massive active star-forming region in the Local group. We use RV measurements of the O-type star populations in 30 Doradus obtained by the VLT-FLAMES Tarantula Survey and the Tarantula Massive Binary Monitoring to identify single and binary O-type runaways. We discuss their rotational properties and qualitatively compare observations with expectations of ejection scenarios. We identify 23 single and one binary O-type runaway objects, most of them outside the main star-forming regions in 30 Doradus. We find an overabundance of rapid rotators (vsini > 200km/s) among the runaway population, providing an explanation of the overabundance of rapidly rotating stars in the 30 Doradus field. Considerations of the projected rotation rates and runaway line-of-sight (los) velocities reveal a conspicuous absence of rapidly rotating (vsini > 210k/ms), fast moving (v_{los} > 60km/s) runaways, and suggest the presence of two different populations of runaway stars: a population of rapidly-spinning but slowly moving runaways and a population of fast moving but slowly rotating ones. These are detected with a ratio close to 2:1 in our sample. We argue that slowly moving but rapidly spinning runaways result from binary ejections, while rapidly moving but slowly spinning runaways could result from dynamical ejections. Given that detection biases will more strongly impact the slow-moving population, our results suggest that the binary evolution scenario dominates the current massive runaway population in 30 Doradus.

astro-ph.SR↗
arXiv2022

Bipolar planetary nebulae from common envelope evolution of binary stars

Asymmetric shapes and evidence for binary central stars suggest a common-envelope origin for many bipolar planetary nebulae. The bipolar components of the nebulae are observed to expand faster than the rest and the more slowly expanding material has been associated with the bulk of the envelope ejected during the common-envelope phase of a stellar binary system. Common-envelope evolution in general remains one of the biggest uncertainties in binary star evolution and the origin of the fast outflow has not been explained satisfactorily. We perform three-dimensional magnetohydrodynamic simulations of common-envelope interaction with the moving-mesh code AREPO. Starting from the plunge-in of the companion into the envelope of an asymptotic giant branch star and covering hundreds of orbits of the binary star system, we are able to follow the evolution to complete envelope ejection. We find that magnetic fields are strongly amplified in two consecutive episodes. First, when the companion spirals in the envelope and, second, when it forms a contact binary with the core of the former giant star. In the second episode, a magnetically-driven, high-velocity outflow of gas is launched self-consistently in our simulations. The outflow is bipolar and the gas is additionally collimated by the ejected common envelope. The resulting structure reproduces typical morphologies and velocities observed in young planetary nebulae. We propose that the magnetic driving mechanism is a universal consequence of common envelope interaction responsible for a substantial fraction of observed planetary nebulae. Such a mechanism likely also exists in the common-envelope phase of other binary stars that lead to the formation of Type Ia supernovae, X-ray binaries and gravitational-wave merger events.

astro-ph.SR↗
arXiv2021

The Tarantula Massive Binary Monitoring V. R 144: a wind-eclipsing binary with a total mass > 140 Msun

R 144 is the visually brightest WR star in the Large Magellanic Cloud (LMC). R 144 was reported to be a binary, making it potentially the most massive binary thus observed. We perform a comprehensive spectral, photometric, orbital, and polarimetric analysis of R 144. R 144 is an eccentric (e=0.51) 74.2-d binary comprising two relatively evolved (age~2 Myr), H-rich WR stars. The hotter primary (WN5/6h, T=50 kK) and the cooler secondary (WN6/7h,T=45kK) have nearly equal masses. The combination of low rotation and H-depletion observed in the system is well reproduced by contemporary evolution models that include boosted mass-loss at the upper-mass end. The systemic velocity of R 144 and its relative isolation suggest that it was ejected as a runaway from the neighbouring R 136 cluster. The optical light-curve shows a clear orbital modulation that can be well explained as a combination of two processes: excess emission stemming from wind-wind collisions and double wind eclipses. Our light-curve model implies an orbital inclination of i=60.4+-1.5deg, resulting in accurately constrained dynamical masses of 74+-4 and 69+-4 Msun. Assuming that both binary components are core H-burning, these masses are difficult to reconcile with the derived luminosities (logL1,2 = 6.44, 6.39 [Lsun]), which correspond to evolutionary masses of the order of 110 and 100Msun, respectively. Taken at face value, our results imply that both stars have high classical Eddington factors of Gamma_e = 0.78+-0.1. If the stars are on the main sequence, their derived radii (~25Rsun) suggest that they are only slightly inflated, even at this high Eddington factor. Alternatively, the stars could be core-He burning, strongly inflated from the regular size of classical Wolf-Rayet stars (~1Rsun), a scenario that could help resolve the observed mass discrepancy.

astro-ph.SR↗
arXiv2021

The young massive SMC cluster NGC 330 seen by MUSE II. Multiplicity properties of the massive-star population

Observations of massive stars in young open clusters (< ~8 Myr) have shown that a majority of them are in binary systems, most of which will interact during their life. Populations of massive stars older than ~20 Myr allow us to probe the outcome of such interactions after many systems have experienced mass and angular momentum transfer. Using multi-epoch integral-field spectroscopy, we investigate the multiplicity properties of the massive-star population in NGC 330 (~40 Myr) in the Small Magellanic Cloud to search for imprints of stellar evolution on the multiplicity properties. From six epochs of VLT/MUSE observations supported by adaptive optics we extract spectra and measure radial velocities for stars brighter than F814W = 19. We identify single-lined spectroscopic binaries through significant RV variability as well as double-lined spectroscopic binaries, and quantify the observational biases for binary detection. The observed spectroscopic binary fraction is 13.2+/-2.0 %. Considering period and mass ratio ranges from log(P)=0.15-3.5, and q = 0.1-1.0, and a representative set of orbital parameter distributions, we find a bias-corrected close binary fraction of 34 +8 -7 %. This seems to decline for the fainter stars, which indicates either that the close binary fraction drops in the B-type domain, or that the period distribution becomes more heavily weighted towards longer orbital periods. Both fractions vary strongly in different regions of the color-magnitude diagram which probably reveals the imprint of the binary history of different groups of stars. We provide the first homogeneous RV study of a large sample of B-type stars at a low metallicity. The overall bias-corrected close binary fraction of B stars in NGC 330 is lower than the one reported for younger Galactic and LMC clusters. More data are needed to establish whether this result from an age or a metallicty effect.

astro-ph.SR↗
arXiv2020

Common-envelope evolution with an asymptotic giant branch star

Common-envelope phases are decisive for the evolution of many binary systems. Of particular interest are cases with asymptotic giant branch (AGB) primary stars, because they are thought to be progenitors of various astrophysical transients. In three-dimensional hydrodynamic simulations with the moving-mesh code AREPO, we study the common-envelope evolution of a $1.0\,M_{\odot}$ early-AGB star with companions of different masses. Although the stellar envelope of the AGB star is less tightly bound than that of a red giant, we find that the release of orbital energy of the core binary is insufficient to eject more than about twenty percent of the envelope mass. Ionization energy released in the expanding envelope, however, can lead to complete envelope ejection. Because recombination proceeds largely at high optical depths in our simulations, it is likely that this effect indeed plays a significant role in the considered systems. The efficiency of mass loss and the final orbital separation of the core binary system depend on the mass ratio between the companion and the primary star. Our results suggest a linear relation between the ratio of final to initial orbital separation and this parameter.

astro-ph.SR↗
arXiv2020

Pre-supernova evolution, compact object masses and explosion properties of stripped binary stars

Most massive stars are born in binary or higher-order multiple systems and exchange mass with a companion during their lives. In particular, the progenitors of a large fraction of compact object mergers, and Galactic neutron stars (NSs) and black holes (BHs) have been stripped off their envelopes by a binary companion. Here, we study the evolution of single and stripped binary stars up to core collapse with the stellar evolution code MESA and their final fates with a parametric supernova (SN) model. We find that stripped binary stars can have systematically different pre-SN structures compared to genuine single stars and thus also different SN outcomes. The bases of these differences are already established by the end of core helium burning and are preserved up to core collapse. We find a non-monotonic pattern of NS and BH formation as a function of CO core mass that is different in single and stripped binary stars. In terms of initial masses, single stars of >35 Msun all form BHs, while this transition is only at 70 Msun in stripped stars. On average, stripped stars give rise to lower NS and BH masses, higher explosion energies, higher kick velocities and higher nickel yields. Within a simplified population synthesis model, we show that our results lead to a significant reduction of the rates of BH-NS and BH-BH mergers with respect to typical assumptions made on NS and BH formation. Therefore, we predict lower detection rates of such merger events by, e.g., advanced LIGO than is often considered. We further show how features in the NS-BH mass distribution of single and stripped stars relate to the chirp-mass distribution of compact object mergers. Further implications of our findings are discussed with respect to the missing red-supergiant problem, a possible mass gap between NSs and BHs, X-ray binaries and observationally inferred nickel masses from Type Ib/c and IIP Sne. [abridged]

astro-ph.SR↗
arXiv2020

Formation of sdB-stars via common envelope ejection by substellar companions

Common envelope (CE) phases in binary systems where the primary star reaches the tip of the red giant branch are discussed as a formation scenario for hot subluminous B-type (sdB) stars. For some of these objects, observations point to very low-mass companions. In hydrodynamical CE simulations with the moving-mesh code AREPO, we test whether low-mass objects can successfully unbind the envelope. The success of envelope removal in our simulations critically depends on whether or not the ionization energy released by recombination processes in the expanding material is taken into account. If this energy is thermalized locally, envelope ejection eventually leading to the formation of an sdB star is possible with companion masses down to the brown dwarf range. For even lower companion masses approaching the regime of giant planets, however, envelope removal becomes increasingly difficult or impossible to achieve. Our results are consistent with current observational constraints on companion masses of sdB stars. Based on a semianalytic model, we suggest a new criterion for the lowest companion mass that is capable of triggering a dynamical response of the primary star thus potentially facilitating the ejection of a common envelope. This gives an estimate consistent with the findings of our hydrodynamical simulations.

astro-ph.SR↗
arXiv2020

Long-term evolution of a magnetic massive merger product

About 10% of stars more massive than ${\approx}\,1.5\,\mathrm{M}_\odot$ have strong, large-scale surface magnetic fields and are being discussed as progenitors of highly-magnetic white dwarfs and magnetars. The origin of these fields remains uncertain. Recent 3D magnetohydrodynamical simulations have shown that strong magnetic fields can be generated in the merger of two massive stars. Here, we follow the long-term evolution of such a 3D merger product in a 1D stellar evolution code. During a thermal relaxation phase after the coalescence, the merger product reaches critical surface rotation, sheds mass and then spins down primarily because of internal mass readjustments. The spin of the merger product after thermal relaxation is mainly set by the co-evolution of the star-torus structure left after coalescence. This evolution is still uncertain, so we also consider magnetic braking and other angular-momentum-gain and -loss mechanisms that may influence the final spin of the merged star. Because of core compression and mixing of carbon and nitrogen in the merger, enhanced nuclear burning drives a transient convective core that greatly contributes to the rejuvenation of the star. Once the merger product relaxed back to the main sequence, it continues its evolution similar to that of a genuine single star of comparable mass. It is a slow rotator that matches the magnetic blue straggler $τ$ Sco. Our results show that merging is a promising mechanism to explain some magnetic massive stars and it may also be key to understand the origin of the strong magnetic fields of highly-magnetic white dwarfs and magnetars.

astro-ph.SR↗
arXiv2020

Properties of OB star-black hole systems derived from detailed binary evolution models

The recent gravitational wave measurements have demonstrated the existence of stellar mass black hole binaries. It is essential for our understanding of massive star evolution to identify the contribution of binary evolution to the formation of double black holes. A promising way to progress is investigating the progenitors of double black hole systems and comparing predictions with local massive star samples such as the population in 30 Doradus in the Large Magellanic Cloud (LMC). Methods. To this purpose, we analyse a large grid of detailed binary evolution models at LMC metallicity with initial primary masses between 10 and 40 Msun, and identify which model systems potentially evolve into a binary consisting of a black hole and a massive main sequence star. We then derive the observable properties of such systems, as well as peculiarities of the OB star component. We find that about 3% of the LMC late O and early B stars in binaries are expected to possess a black hole companion, when assuming stars with a final helium core mass above 6.6 M to form black holes. While the vast majority of them may be X-ray quiet, our models suggest that these may be identified in spectroscopic binaries, either by large amplitude radial velocity variations ( > 50 km s ) and simultaneous nitrogen surface enrichment, or through a moderate radial velocity ( > 10 km/s ) and simultaneously rapid rotation of the OB star. The predicted mass ratios are such that main sequence companions could be excluded in most cases. A comparison to the observed OB+WR binaries in the LMC, Be/X-ray binaries, and known massive BH binaries supports our conclusion. We expect spectroscopic observations to be able to test key assumptions in our models, with important implications for massive star evolution in general, and for the formation of double-black hole mergers in particular.

astro-ph.SR↗
arXiv2019

The Tarantula Massive Binary Monitoring: III. Atmosphere analysis of double-lined spectroscopic systems

Accurate stellar parameters of individual objects in binary systems are essential to constrain the effects of binarity on stellar evolution. These parameters serve as a prerequisite to probing existing and future theoretical evolutionary models. We aim to derive the atmospheric parameters of the 31 SB2s in the TMBM sample. This sample, composed of detached, semi-detached and contact systems with at least one of the components classified as an O star, is an excellent test-bed to study how binarity can impact our knowledge of the evolution of massive stars. 32 epochs of FLAMES/GIRAFFE spectra are analysed using spectral disentangling to construct the individual spectra of 62 components. We apply the CMFGEN atmosphere code to determine their stellar parameters and their He, C and N surface abundances. From these properties, we show that the effects of tides on chemical mixing are limited. Components on longer-period orbits show higher nitrogen enrichment at their surface than those on shorter-period orbits, in contrast to expectations of rotational or tidal mixing, implying that other mechanisms play a role in this process. Components filling their Roche lobe are mass donors. They exhibit higher nitrogen content at their surface and rotate more slowly than their companions. By accreting new material, their companions spin faster and are rejuvenated. Their locations in the N-vsini diagram tend to show that binary products are good candidates to populate the two groups of stars (slowly rotating, nitrogen-enriched and rapidly rotating non-enriched) that cannot be reproduced through single-star population synthesis. This sample is the largest sample of binaries to be studied in such a homogeneous way. The study of these objects gives us strong observational constraints to test theoretical binary evolutionary tracks.

astro-ph.SR↗