Rejuvenation of stellar mergers and the origin of magnetic fields in massive stars

Abstract

Approximately 10% of massive OBA main-sequence (MS) and pre-MS stars harbour strong, large-scale magnetic fields. At the same time there is a dearth of magnetic stars in close binaries. A process generating strong magnetic fields only in some stars must be responsible with the merging of pre-MS and MS stars being suggested as one such channel. Stars emerging from the coalescence of two MS stars are rejuvenated, appearing younger than they are. They can therefore be identified by comparison with reference clocks. Here we predict the rejuvenation of MS merger products over a wide range of masses and binary configurations calibrated to smoothed-particle-hydrodynamical merger models. We find that the rejuvenation is of the order of the nuclear timescale and is strongest in the lowest-mass mergers and the most evolved binary progenitors with the largest mass ratios. These predictions allow us to put constraints on the binary progenitors of merger products. We show that the magnetic stars HR 2949 and $\tau$ Sco are younger than the potential binary companion HR 2948 and the Upper-Sco association, respectively, making them promising merger candidates. We find that the age discrepancies and the potential binary progenitors of both are consistent with them being rejuvenated merger products, implying that their magnetic fields may originate from this channel. Searching for age discrepancies in magnetic stars is therefore a powerful way to explore which fraction of magnetic stars may have obtained their strong magnetic field in MS mergers and to improve our understanding of magnetism in massive stars and their remnants.

12 pages, 5 figures, 3 tables; accepted for publication in MNRAS

References in corpus (22)

• Pre-Supernova Evolution of Massive Single and Binary Stars
• The surprising magnetic topology of tauSco: fossil remnant or dynamo output?
• Binary Star Origin of High Field Magnetic White Dwarfs
• The VLT-FLAMES survey of massive stars: rotation and nitrogen enrichment as the key to understanding massive star evolution
• The VLT-FLAMES survey of massive stars: atmospheric parameters and rotational velocity distributions for B-type stars in the Magellanic Clouds
• BONNSAI: a Bayesian tool for comparing stars with stellar evolution models
• A search for strong, ordered magnetic fields in Herbig Ae/Be stars
• Abundance analysis of prime B-type targets for asteroseismology I. Nitrogen excess in slowly-rotating beta Cephei stars
• Nitrogen enrichment, boron depletion and magnetic fields in slowly-rotating B-type dwarfs
• B fields in OB stars (BOB): low-resolution FORS2 spectropolarimetry of the first sample of 50 massive stars
• Evolution of Mass Functions of Coeval Stars through Wind Mass Loss and Binary Interactions
• Magnetic field measurements of O stars with FORS1 at the VLT
• Fundamental properties of nearby single early B-type stars
• Magnetic Field Generation in Stars
• High resolution optical spectroscopy of Plaskett's star
• Evolution of stellar collision products in open clusters. II. A grid of low-mass collisions
• On Rejuvenation in Massive Binary Systems
• Detection of magnetic fields in both B-type components of the $\epsilon$ Lupi system: a new constraint on the origin of fossil fields?
• The BinaMIcS project: understanding the origin of magnetic fields in massive stars through close binary systems
• New insights into the nature of the peculiar star theta Carinae
• The magnetic field and spectral variability of the He-weak star HR 2949
• The origin of magnetic fields in hot stars

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• The Magnetic Early B-type Stars III: A main sequence magnetic, rotational, and magnetospheric biography
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• The diverse lives of progenitors of hydrogen-rich core-collapse supernovae: the role of binary interaction
• Stellar mergers as the origin of the blue main-sequence band in young star clusters
• Long-term evolution of a magnetic massive merger product
• Evolution of accretor stars in massive binaries: broader implications from modeling ζ Ophiuchi
• Effects of close binary evolution on the main-sequence morphology of young star clusters
• The effects of surface fossil magnetic fields on massive star evolution: I. Magnetic field evolution, mass-loss quenching and magnetic braking
• A census of massive stars in NGC 346. Stellar parameters and rotational velocities
• The VLT-FLAMES Tarantula Survey XXVI: Properties of the O-dwarf population in 30 Doradus
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• The impact of non-dipolar magnetic fields in core-collapse supernovae
• The effects of surface fossil magnetic fields on massive star evolution: II. Implementation of magnetic braking in MESA and implications for the evolution of surface rotation in OB stars
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• The young massive SMC cluster NGC 330 seen by MUSE. I. Observations and stellar content
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• Electron Capture Supernovae From Close Binary Systems
• Evidence of magnetic field decay in massive main-sequence stars
• Pre-supernova evolution and final fate of stellar mergers and accretors of binary mass transfer
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• NGC 6067: a young and massive open cluster with high metallicity
• JWST's PEARLS: Mothra, a new kaiju star at z=2.091 extremely magnified by MACS0416, and implications for dark matter models
• The MiMeS survey of Magnetism in Massive Stars: Magnetic properties of the O-type star population
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• The VLT-FLAMES Tarantula Survey: XXVIII. Nitrogen abundances for apparently single dwarf and giant B-type stars with small projected rotational velocities
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• HD66051: the first eclipsing binary hosting an early-type magnetic star
• Comparison of Theoretical Starburst Photoionisation Models for Optical Diagnostics
• Is Betelgeuse the Outcome of a Past Merger?
• Fossil field decay due to nonlinear tides in massive binaries
• Very massive stars in not so massive clusters
• The effects of surface fossil magnetic fields on massive star evolution: IV. Grids of models at Solar, LMC, and SMC metallicities
• The IACOB project X. Large-scale quantitative spectroscopic analysis of Galactic luminous blue stars
• The IACOB project VIII. Searching for empirical signatures of binarity in fast-rotating O-type stars
• The effects of surface fossil magnetic fields on massive star evolution: III. The case of $\tau$ Sco
• Modeling overcontact binaries, I. The effect of tidal deformation
• Binary black hole mergers from merged stars in the Galactic field
• IR nebulae around bright massive stars as indicators for binary interactions
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• Origin of a massive hyper-runaway subgiant star LAMOST-HVS1 -- implication from Gaia and follow-up spectroscopy
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• Mapping the core of the Tarantula Nebula with VLT-MUSE II. The spectroscopic Hertzsprung-Russell diagram of OB stars in NGC 2070
• Populations of evolved massive binary stars in the Small Magellanic Cloud I: Predictions from detailed evolution models
• Mechanical feedback from stellar winds with an application to galaxy formation at high redshift
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• The population synthesis of Wolf-Rayet stars involving binary merger channels
• Rotation signature of TESS B-type stars. A comprehensive analysis
• Detection of an extremely strong magnetic field in the double-degenerate binary merger product HD 144941
• Extreme mass ratios and fast rotation in three massive binaries
• MOBSTER -- IV. Detection of a new magnetic B-type star from follow-up spectropolarimetric observations of photometrically selected candidates
• CPD-64 2731: a massive spun-up and rejuvenated high-velocity runaway star
• Are magnetic fields universal in O-type multiple systems?
• Collision-induced mass loss and mass gain on an extremely massive star. An analytical approach and a static proto-globular cluster test-case
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• The significant contribution of supersoft X-ray Sources to the nebular HeII line emission
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• Detailed evolutionary models of massive contact binaries: I. Model grids and synthetic populations for the Magellanic Clouds
• X-ray emission from candidate stellar merger remnant TYC 2597-735-1 and its Blue Ring Nebula
• Discovery of O stars in the tidal Magellanic Bridge: Stellar parameters, abundances, and feedback of the nearest metal-poor massive stars and their implication for the Magellanic System ecology
• Probabilistic Zeeman-Doppler imaging of stellar magnetic fields: I. Analysis of tau Scorpii in the weak-field limit
• Quantifying Systematic Age Discrepancies in Very Young Star Clusters
• Can the Anomalous Magnetic Braking of Ap/Bp Stars Explain the Orbital Decay of Algol-type Binaries?
• Discovery and analysis of three magnetic hot subdwarf stars: evidence for merger-induced magnetic fields