scholarly journals Missing red supergiants and carbon burning

2020 ◽  
Vol 492 (2) ◽  
pp. 2578-2587 ◽  
Author(s):  
Tuguldur Sukhbold ◽  
Scott Adams
Keyword(s):  
Mixing Efficiency ◽  
Core Collapse ◽  
Direct Imaging ◽  
Transition Range ◽  
Central Carbon ◽  
Red Supergiants ◽  
Supernova Explosions ◽  
Uncertain Input ◽  
Carbon Burning ◽  
Radiative Regime

ABSTRACT Recent studies on direct imaging of Type II core-collapse supernova progenitors indicate a possible threshold around MZAMS ∼ 16–20 M⊙, where red supergiants (RSG) with larger birth masses do not appear to result in supernova explosions and instead implode directly into a black hole. In this study, we argue that it is not a coincidence that this threshold closely matches the critical transition of central carbon burning in massive stars from the convective to radiative regime. In lighter stars, carbon burns convectively in the centre and result in compact final pre-supernova cores that are likely to result in explosions, while in heavier stars after the transition, it burns as a radiative flame and the stellar cores become significantly harder to explode. Using the $\rm {\small {kepler}}$ code we demonstrate the sensitivity of this transition to the rate of 12C(α, γ)16O reaction and the overshoot mixing efficiency, and we argue that the upper mass limit of exploding RSG could be employed to constrain uncertain input physics of massive stellar evolution calculations. The initial mass corresponding to the central carbon burning transition range from 14 to 26 M⊙ in recently published models from various groups and codes, and only a few are in agreement with the estimates inferred from direct imaging studies.

scholarly journals Core Collapse Supernova Models and Nucleosynthesis

2013 ◽  
Vol 9 (S296) ◽  
pp. 27-36
Author(s):  
Ken'ichi Nomoto
Keyword(s):  
Big Bang ◽  
Elemental Abundance ◽  
Core Collapse ◽  
Solar Abundance ◽  
First Stars ◽  
Abundance Pattern ◽  
Core Collapse Supernova ◽  
Abundance Patterns ◽  
Supernova Explosions ◽  
The Big Bang

AbstractAfter the Big Bang, production of heavy elements in the early Universe takes place in the first stars and their supernova explosions. The nature of the first supernovae, however, has not been well understood. The signature of nucleosynthesis yields of the first supernovae can be seen in the elemental abundance patterns observed in extremely metal-poor stars. Interestingly, those abundance patterns show some peculiarities relative to the solar abundance pattern, which should provide important clues to understanding the nature of early generations of supernovae. We review the recent results of the nucleosynthesis yields of massive stars. We examine how those yields are affected by some hydrodynamical effects during the supernova explosions, namely, explosion energies from those of hypernovae to faint supernovae, mixing and fallback of processed materials, asphericity, etc. Those parameters in the supernova nucleosynthesis models are constrained from observational data of supernovae and metal-poor stars.

NEUTRINO OSCILLATION IN SUPERNOVA AND GRB NUCLEOSYNTHESIS

2008 ◽  
Vol 23 (17n20) ◽  
pp. 1409-1418 ◽  
Author(s):  
TOSHITAKA KAJINO ◽  
TAKAHIRO SASAQUI ◽  
TAKASHI YOSHIDA ◽  
WAKO AOKI
Keyword(s):  
Black Hole ◽  
Gamma Ray ◽  
Light Element ◽  
Core Collapse ◽  
Mass Hierarchy ◽  
Solar Abundance ◽  
Abundance Pattern ◽  
Mixing Angle ◽  
Normal Mass ◽  
Supernova Explosions

Neutrinos play the critical roles in nucleosyntheses of light-to-heavy mass elements in core-collapse supernovae (SNe). The light element synthesis is affected strongly by neutrino oscillations (MSW effect) through the ν-process in outer layers of supernova explosions. Specifically the 7 Li and 11 B yields increase by factors of 1.9 and 1.3 respectively in the case of large mixing angle solution, normal mass hierarchy, and sin 2 2θ13 = 2 × 10−3 compared to those without the oscillations. In the case of inverted mass hierarchy or nonadiabatic 13-mixing resonance, the increment of their yields is much smaller. We thus propose that precise constraint on mass hierarchy and sin 2 2θ13 is given by future observations of Li / B ratio or Li abundance in stars and presolar grains which are made from supernova ejecta. Gamma ray burst (GRB) nucleosynthesis in contrast is not affected strongly by thermal neutrinos from the central core which culminates in black hole (BH), although the effect of neutrinos from proto-neutron star prior to black hole formation is still unknown. We calculate GRB nucleosynthesis by turning off the thermal neutrinos and find that the abundance pattern is totally different from ordinary SN nucleosynthesis which satisfies the universality to the solar abundance pattern.

scholarly journals The progenitors of core-collapse supernovae

2016 ◽  
Vol 12 (S329) ◽  
pp. 32-38
Author(s):  
Morgan Fraser
Keyword(s):  
Black Hole ◽  
Binary Systems ◽  
Massive Star ◽  
Core Collapse ◽  
Red Supergiants ◽  
To Come

AbstractLinking core-collapse SNe to their stellar progenitors is a major ongoing challenge. To date, H rich Type IIP SNe have been shown to come from red supergiants, while there is increasing evidence that the majority of stripped envelope SNe come from binary systems. The first candidates for failed SNe, where a massive star collapses to form a black hole without a bright optical display have been identified, while the range of outbursts and eruptions from pre-SN stars are just beginning to be revealed.

scholarly journals The evolution of ultra-massive white dwarfs

2019 ◽  
Vol 625 ◽  
pp. A87 ◽  
Author(s):  
María E. Camisassa ◽  
Leandro G. Althaus ◽  
Alejandro H. Córsico ◽  
Francisco C. De Gerónimo ◽  
Marcelo M. Miller Bertolami ◽  
...  
Keyword(s):  
Phase Separation ◽  
White Dwarf ◽  
White Dwarfs ◽  
Outer Boundary ◽  
Asymptotic Giant Branch ◽  
Type Ia ◽  
Chemical Profiles ◽  
Supernova Explosions ◽  
Carbon Burning ◽  
The Impact

Ultra-massive white dwarfs are powerful tools used to study various physical processes in the asymptotic giant branch (AGB), type Ia supernova explosions, and the theory of crystallization through white dwarf asteroseismology. Despite the interest in these white dwarfs, there are few evolutionary studies in the literature devoted to them. Here we present new ultra-massive white dwarf evolutionary sequences that constitute an improvement over previous ones. In these new sequences we take into account for the first time the process of phase separation expected during the crystallization stage of these white dwarfs by relying on the most up-to-date phase diagram of dense oxygen/neon mixtures. Realistic chemical profiles resulting from the full computation of progenitor evolution during the semidegenerate carbon burning along the super-AGB phase are also considered in our sequences. Outer boundary conditions for our evolving models are provided by detailed non-gray white dwarf model atmospheres for hydrogen and helium composition. We assessed the impact of all these improvements on the evolutionary properties of ultra-massive white dwarfs, providing updated evolutionary sequences for these stars. We conclude that crystallization is expected to affect the majority of the massive white dwarfs observed with effective temperatures below 40 000 K. Moreover, the calculation of the phase separation process induced by crystallization is necessary to accurately determine the cooling age and the mass-radius relation of massive white dwarfs. We also provide colors in the Gaia photometric bands for our H-rich white dwarf evolutionary sequences on the basis of new model atmospheres. Finally, these new white dwarf sequences provide a new theoretical frame to perform asteroseismological studies on the recently detected ultra-massive pulsating white dwarfs.

scholarly journals Massive stars burning helium: the numbers of WR stars and red supergiants in galaxies

1981 ◽  
Vol 59 ◽  
pp. 283-287
Author(s):  
A. Maeder
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Short Note ◽  
Evolutionary Models ◽  
Helium Burning ◽  
Red Supergiants ◽  
Low Mass ◽  
Age Sequence ◽  
Carbon Burning ◽  
Loss Rates

We have calculated evolutionary models of massive stars in the range 15-120 Mʘ from the zero-age sequence up to the end of the carbon burning stage (Maeder, 1981). Three sets of models with different mass loss rates Ṁ have been computed; the adopted parametrisation of Ṁ is fitted on the observations and thus the expression for Ṁ differs according to the location of the stars in the HRD.In this short note we concentrate on the location of the He-burning stars in the HRD. The helium burning phase, which lasts 8 to 10% of the MS phase, is spent mainly as red supergiants (RSG) and as WR stars (note that for low mass loss, the time spent as A-G supergiants becomes longer).

scholarly journals Effects of Small-Scale Fluctuations of Neutrino Flux in Supernova Explosions

2005 ◽  
Vol 192 ◽  
pp. 309-314
Author(s):  
Hideki Madokoro ◽  
Tetsuya Shimizu ◽  
Yuko Motizuki
Keyword(s):  
Neutrino Flux ◽  
Explosion Energy ◽  
Small Scale ◽  
Core Collapse ◽  
Effective Mechanism ◽  
Core Collapse Supernova ◽  
Neutrino Radiation ◽  
Spherical Explosion ◽  
Supernova Explosions ◽  
Neutrino Luminosity

SummaryWe examine effects of small-scale fluctuations with angle in the neutrino radiation in core-collapse supernova explosions. As the mode number of fluctuations increases, the results approach those of spherical explosion. We conclude that global anisotropy of the neutrino radiation is the most effective mechanism of increasing the explosion energy when the total neutrino luminosity is given.

scholarly journals Acoustic wave generation in collapsing massive stars with convective shells

2020 ◽  
Vol 493 (3) ◽  
pp. 3496-3512 ◽  
Author(s):  
Ernazar Abdikamalov ◽  
Thierry Foglizzo
Keyword(s):  
Acoustic Waves ◽  
Massive Stars ◽  
Core Collapse ◽  
Core Collapse Supernova ◽  
Stellar Collapse ◽  
Acoustic Wave Generation ◽  
Supernova Explosions ◽  
Accretion Shock ◽  
Stationary Background ◽  
Hydrodynamics Equations

ABSTRACT The convection that takes place in the innermost shells of massive stars plays an important role in the formation of core-collapse supernova explosions. Upon encountering the supernova shock, additional turbulence is generated, amplifying the explosion. In this work, we study how the convective perturbations evolve during the stellar collapse. Our main aim is to establish their physical properties right before they reach the supernova shock. To this end, we solve the linearized hydrodynamics equations perturbed on a stationary background flow. The latter is approximated by the spherical transonic Bondi accretion, while the convective perturbations are modelled as a combination of entropy and vorticity waves. We follow their evolution from large radii, where convective shells are initially located, down to small radii, where they are expected to encounter the accretion shock above the proto-neutron star. Considering typical vorticity perturbations with a Mach number ∼0.1 and entropy perturbations with magnitude ∼0.05kb/baryon, we find that the advection of these perturbations down to the shock generates acoustic waves with a relative amplitude $\delta {\rm p}/\gamma {\rm p} \lesssim 10{{\ \rm per\ cent}}$, in agreement with published numerical simulations. The velocity perturbations consist of contributions from acoustic and vorticity waves with values reaching ${\sim}10{{\ \rm per\ cent}}$ of the sound speed ahead of the shock. The perturbation amplitudes decrease with increasing ℓ and initial radii of the convective shells.

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