Evolution of rotation in rapidly rotating early-type stars during the main sequence with 2D models

Gagnier, D.; Rieutord, M.; Charbonnel, C.; Putigny, Bertrand; Lara, F. Espinosa

doi:10.1051/0004-6361/201832581

Cited by 24 publications

(23 citation statements)

References 27 publications

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“…For massive stars, the evolution of the magnetic field in the core depends both on the coupling of different stellar layers through, for example, a magnetic dynamo , or through mass loss from winds. Mass loss depends upon metallicity, and there is a tendency to argue that angular momentum loss from winds is higher at higher metallicities where mass loss from winds is highest, but anisotropies in this mass loss make it both difficult to determine the total angular momentum loss and the dependence of this angular momentum loss on winds [Georgy et al, 2013a, Gagnier et al, 2019. For all but the last scenario, our current understanding of the magnetic dynamo makes it difficult to get high enough angular momentum profiles for the magnetar or neutron star accretion disk models to work.…”

Section: Massive Star Progenitorsmentioning

confidence: 99%

Understanding the engines and progenitors of gamma-ray bursts

et al. 2019

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Our understanding of the engines and progenitors of gamma-ray bursts has expanded through the ages as a broader set of diagnostics has allowed us to test our understanding of these objects. Here we review the history of the growth in our understanding, focusing on 3 leading engines and 9 potential progenitors. The first gravitational wave detection of a short burst is the latest in a series of breakthrough observations shaping this understanding and we study the importance of multi-diagnostic, multi-messenger observations on these engines and their progenitors. Our understanding based on a detailed study of nearby bursts can be applied to make predictions for the trends expected as we begin to observe high redshift bursts and we discuss these trends.PACS. 95.85.Pw gamma-ray -95.85.Sz gravitational radiation, magnetic fields, and other observations

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Section: Massive Star Progenitorsmentioning

confidence: 99%

Understanding the engines and progenitors of gamma-ray bursts

et al. 2019

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“…Nontraditional effects can be particularly important for stellar structure configurations where the Coriolis acceleration can compete with the Archimedean force in the direction of both entropy and chemical stratification, for instance during the formation of the radiative core of pre-main-sequence, lowmass stars or in the radiative envelope of rapidly rotating upper main-sequence stars. These regimes should be treated properly to build robust one-or two-dimensional (1D or 2D) secular models of the evolution of rotating stars (e.g., Ekström et al 2012;Amard et al 2019;Gagnier et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Horizontal shear instabilities in rotating stellar radiation zones

Park

Prat

Mathis

et al. 2021

A&A

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Context. Stellar interiors are the seat of efficient transport of angular momentum all along their evolution. In this context, understanding the dependence of the turbulent transport triggered by the instabilities of the vertical and horizontal shears of the differential rotation in stellar radiation zones as a function of their rotation, stratification, and thermal diffusivity is mandatory. Indeed, it constitutes one of the cornerstones of the rotational transport and mixing theory, which is implemented in stellar evolution codes to predict the rotational and chemical evolutions of stars. Aims. We investigate horizontal shear instabilities in rotating stellar radiation zones by considering the full Coriolis acceleration with both the dimensionless horizontal Coriolis component f̃ and the vertical component f. Methods. We performed a linear stability analysis using linearized equations derived from the Navier-Stokes and heat transport equations in the rotating nontraditional f-plane. We considered a horizontal shear flow with a hyperbolic tangent profile as the base flow. The linear stability was analyzed numerically in wide ranges of parameters, and we performed an asymptotic analysis for large vertical wavenumbers using the Wentzel-Kramers-Brillouin-Jeffreys (WKBJ) approximation for nondiffusive and highly-diffusive fluids. Results. As in the traditional f-plane approximation, we identify two types of instabilities: the inflectional and inertial instabilities. The inflectional instability is destabilized as f̃ increases and its maximum growth rate increases significantly, while the thermal diffusivity stabilizes the inflectional instability similarly to the traditional case. The inertial instability is also strongly affected; for instance, the inertially unstable regime is also extended in the nondiffusive limit as 0 < f < 1 + f̃ 2/N2, where N is the dimensionless Brunt-Väisälä frequency. More strikingly, in the high thermal diffusivity limit, it is always inertially unstable at any colatitude θ except at the poles (i.e., 0° < θ < 180°). We also derived the critical Reynolds numbers for the inertial instability using the asymptotic dispersion relations obtained from the WKBJ analysis. Using the asymptotic and numerical results, we propose a prescription for the effective turbulent viscosities induced by the inertial and inflectional instabilities that can be possibly used in stellar evolution models. The characteristic time of this turbulence is short enough so that it is efficient to redistribute angular momentum and to mix chemicals in stellar radiation zones.

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“…This is probably justified by the strong influence of the magnetic torques implemented in the work by Farmer et al (2015), which significantly inhibited the spin-up of model cores. We note that our knowledge of this phenomenon in stellar evolution is still poorly known and further research has to be done to completely understand the behavior of magnetic fields and rotation (Gagnier et al 2019).…”

Section: Evolutionary and Pulsational Codesmentioning

confidence: 99%

The formation of ultra-massive carbon-oxygen core white dwarfs and their evolutionary and pulsational properties

Althaus

Gil‐Pons

Córsico

et al. 2021

A&A

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Context. The existence of ultra-massive white dwarf stars, MWD ≳ 1.05 M⊙, has been reported in several studies. These white dwarfs are relevant for the role they play in type Ia supernova explosions, the occurrence of physical processes in the asymptotic giant-branch phase, the existence of high-field magnetic white dwarfs, and the occurrence of double-white-dwarf mergers. Aims. We aim to explore the formation of ultra-massive, carbon-oxygen core white dwarfs resulting from single stellar evolution. We also intend to study their evolutionary and pulsational properties and compare them with those of the ultra-massive white dwarfs with oxygen-neon cores resulting from carbon burning in single progenitor stars, and with binary merger predictions. The aim is to provide a theoretical basis that can eventually help to discern the core composition of ultra-massive white dwarfs and the circumstances of their formation. Methods. We considered two single-star evolution scenarios for the formation of ultra-massive carbon-oxygen core white dwarfs, which involve the rotation of the degenerate core after core helium burning and reduced mass-loss rates in massive asymptotic giant-branch stars. We find that reducing standard mass-loss rates by a factor larger than 5−20 yields the formation of carbon-oxygen cores more massive than 1.05 M⊙ as a result of the slow growth of carbon-oxygen core mass during the thermal pulses. We also performed a series of evolutionary tests of solar-metallicity models with initial masses between 4 and 9.5 M⊙ and with different core rotation rates. We find that ultra-massive carbon-oxygen core white dwarfs are formed even for the lowest rotation rates we analyzed, and that the range of initial masses leading to these white dwarfs widens as the rotation rate of the core increases, whereas the initial mass range for the formation of oxygen-neon core white dwarfs decreases significantly. Finally, we compared our findings with the predictions from ultra-massive white dwarfs resulting from the merger of two equal-mass carbon-oxygen core white dwarfs, by assuming complete mixing between them and a carbon-oxygen core for the merged remnant. Results. These two single-evolution scenarios produce ultra-massive white dwarfs with different carbon-oxygen profiles and different helium contents, thus leading to distinctive signatures in the period spectrum and mode-trapping properties of pulsating hydrogen-rich white dwarfs. The resulting ultra-massive carbon-oxygen core white dwarfs evolve markedly slower than their oxygen-neon counterparts. Conclusions. Our study strongly suggests the formation of ultra-massive white dwarfs with carbon-oxygen cores from a single stellar evolution. We find that both the evolutionary and pulsation properties of these white dwarfs are markedly different from those of their oxygen-neon core counterparts and from those white dwarfs with carbon-oxygen cores that might result from double-degenerate mergers. This can eventually be used to discern the core composition of ultra-massive white dwarfs and their formation scenario.

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Evolution of rotation in rapidly rotating early-type stars during the main sequence with 2D models

Cited by 24 publications

References 27 publications

Understanding the engines and progenitors of gamma-ray bursts

Understanding the engines and progenitors of gamma-ray bursts

Horizontal shear instabilities in rotating stellar radiation zones

The formation of ultra-massive carbon-oxygen core white dwarfs and their evolutionary and pulsational properties

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