Thermohaline mixing in super-AGB stars

We study explosion characteristics of ultra-stripped supernovae (SNe), which are candidates of SNe generating binary neutron stars (NSs). As a first step, we perform stellar evolutionary simulations of bare carbon-oxygen cores of mass from 1.45 to 2.0 M ⊙ until the iron cores become unstable and start collapsing. We then perform axisymmetric hydrodynamics simulations with spectral neutrino transport using these stellar evolution outcomes as initial conditions. All models exhibit successful explosions driven by neutrino heating. The diagnostic explosion energy, ejecta mass, Ni mass, and NS mass are typically ∼ 10 50 erg, ∼ 0.1M ⊙ , ∼ 0.01M ⊙ , and ≈ 1.3M ⊙ , which are compatible with observations of rapidly-evolving and luminous transient such as SN 2005ek. We also find that the ultra-stripped SN is a candidate for producing the secondary low-mass NS in the observed compact binary NSs like PSR J0737-3039.

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“…We also take into account thermohaline mixing (e.g. Siess 2009) and the diffusion coefficient is adopted from Eq. (2) in Siess (2009).…”

Section: Stellar Evolution and Progenitor Structuresmentioning

confidence: 99%

“…Siess 2009) and the diffusion coefficient is adopted from Eq. (2) in Siess (2009). The initial chemical compositions of the CO cores are evaluated by those after the He burning with the metallicity Z = 0.02.…”

Section: Stellar Evolution and Progenitor Structuresmentioning

confidence: 99%

Neutrino-driven explosions of ultra-stripped Type Ic supernovae generating binary neutron stars

Suwa

Yoshida

Shibata

et al. 2015

Mon. Not. R. Astron. Soc.

102

116

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“…The treatment of convection is based on the mixing length theory (MLT) as described in Cox & Giuli (1968) with the parameter α mlt = 1.75 calibrated from our solar fit model. Nonstandard mixing processes can also be taken into account, in particular the treatment of thermohaline mixing as described in Siess (2009), diffusive overshooting (Siess et al 2002) and semiconvection (Langer et al 1985). In case of convective mixing, the diffusion coefficient in Eq.…”

Section: Input Stellar Physicsmentioning

confidence: 99%

BINSTAR: a new binary stellar evolution code

Siess

Izzard

Davis

et al. 2013

A&A

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We provide a detailed description of a new stellar evolution code, BINSTAR, which has been developed to study interacting binaries. Based on the stellar evolution code STAREVOL, it is specifically designed to study low-and intermediate-mass binaries. We describe the state-of-the-art input physics, which includes treatments of tidal interactions, mass transfer and angular momentum exchange within the system. A generalised Henyey method is used to solve simultaneously the stellar structure equations of each component as well as the separation and eccentricity of the orbit. Test simulations for cases A and B mass transfer are presented and compared with available models. The results of the evolution of Algol systems are in remarkable agreement with the calculations of the Vrije Universiteit Brussel (VUB) group, thus validating our code. We also computed a large grid of models for various masses (2 ≤ M/M ≤ 20) and seven metallicities (Z = 0.0001, 0.001, 0.004, 0.008, 0.01, 0.02, 0.03) to provide a useful analytical parameterisation of the tidal torque constant E 2 , which allows the determination of the circularisation and synchronisation timescales for stars with a radiative envelope and convective core. The evolution of E 2 during the main sequence shows noticeable differences compared to available models. In particular, our new calculations indicate that the circularisation timescale is constant during core hydrogen burning. We also show that E 2 weakly depends on core overshooting but is substantially increased when the metallicity becomes lower.

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“…Garcia-Berro et al 1997;Siess 2006), the effects of overshooting (Gil-Pons et al 2007), semiconvection (Poelarends et al 2008), or thermohaline mixing (Siess 2009). The start of electron captures reactions in the oxygen-neon (ONe) core and the URCA process have also been investigated (Ritossa et al 1999), and non-solar models were computed and their main properties analysed (e.g.…”

Section: Introductionmentioning

confidence: 99%

Evolution of massive AGB stars

Siess

2010

A&A

Self Cite

188

323

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Aims. We present the first simulations of the full evolution of super-AGB stars through the entire thermally pulsing AGB phase. We analyse their structural and evolutionary properties and determine the first SAGB yields.Methods. Stellar models of various initial masses and metallicities were computed using standard physical assumptions which prevents the third dredge-up from occurring. A postprocessing nucleosynthesis code was used to compute the SAGB yields, to quantify the effect of the third dredge-up (3DUP), and to assess the uncertainties associated with the treatment of convection.Results. Owing to their massive oxygen-neon core, SAGB stars suffer weak thermal pulses, have very short interpulse periods and develop very high temperatures at the base of their convective envelope (up to 140 × 10 8 K), leading to very efficient hot bottom burning. SAGB stars are consequently heavy manufacturers of 4 He, 13 C, and 14 N. They are also able to inject significant amounts of 7 Li, 17 O, 25 Mg, and 26,27 Al in the interstellar medium. The 3DUP mainly affects the CNO yields, especially in the lower metallicity models. Our post-processing simulations also indicate that changes in the temperature at the base of the convective envelope, which would result from a change in the efficiency of convective energy transport, have a dramatic impact on the yields and represent another major source of uncertainty.

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Thermohaline mixing in super-AGB stars

Cited by 46 publications

References 28 publications

Neutrino-driven explosions of ultra-stripped Type Ic supernovae generating binary neutron stars

Neutrino-driven explosions of ultra-stripped Type Ic supernovae generating binary neutron stars

BINSTAR: a new binary stellar evolution code

Evolution of massive AGB stars

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