scholarly journals The Core-Degenerate Scenario for Type Ia Supernovae

2011 ◽  
Vol 7 (S281) ◽  
pp. 72-75 ◽  
Author(s):  
Noam Soker
Keyword(s):  
Critical Mass ◽  
Asymptotic Giant Branch ◽  
Type Ia Supernovae ◽  
Star Forming ◽  
The Core ◽  
Stellar Formation ◽  
Merger Process ◽  
Type Ia ◽  
The Common ◽  
Ia Supernovae

AbstractIn the core-degenerate (CD) scenario for the formation of Type Ia supernovae (SNe Ia) the Chandrasekhar or super-Chandrasekhar mass white dwarf (WD) is formed at the termination of the common envelope phase or during the planetary nebula phase, from a merger of a WD companion with the hot core of a massive asymptotic giant branch (AGB) star. The WD is destroyed and accreted onto the more massive core. In the CD scenario the rapidly rotating WD is formed shortly after the stellar formation episode, and the delay from stellar formation to explosion is basically determined by the spin-down time of the rapidly rotating merger remnant. The spin-down is due to the magneto-dipole radiation torque. Several properties of the CD scenario make it attractive compared with the double-degenerate (DD) scenario. (1) Off-center ignition of carbon during the merger process is not likely to occur. (2) No large envelope is formed. Hence avoiding too much mass loss that might bring the merger remnant below the critical mass. (3) This model explains the finding that more luminous SNe Ia occur preferentially in star forming galaxies.

scholarly journals Structure of a massive common envelope in the common-envelope wind model for Type Ia supernovae

2020 ◽  
Vol 633 ◽  
pp. A41
Author(s):  
Ren Song ◽  
Xiangcun Meng ◽  
Philipp Podsiadlowski ◽  
Yingzhen Cui
Keyword(s):  
Asymptotic Giant Branch ◽  
Dominant Factor ◽  
Lower Envelope ◽  
Type Ia Supernovae ◽  
Mixing Length ◽  
Common Envelope ◽  
Heating Source ◽  
Type Ia ◽  
The Common ◽  
Ia Supernovae

Context. Although Type Ia supernovae (SNe Ia) are important in many astrophysical fields, the nature of their progenitors is still unclear. A new version of the single-degenerate model has been developed recently, the common-envelope wind (CEW) model, in which the binary is enshrouded in a common envelope (CE) during the main accretion phase. This model is still in development and has a number of open issues, for example what is the exact appearance of such a system during the CE phase? Aims. In this paper we investigate this question for a system with a massive CE. Methods. We use a thermally pulsing asymptotic giant branch (TPAGB) star with a CO core of 0.976 M⊙ and an envelope of 0.6 M⊙ to represent the binary system. The effects of the companion’s gravity and the rotation of the CE are mimicked by modifying the gravitational constant. The energy input from the friction between the binary and the CE is taken into account by an extra heating source. Results. For a thick envelope, the modified TPAGB star looks similar to a canonical TPAGB star but with a smaller radius, a higher effective temperature, and a higher surface luminosity. This is primarily caused by the effect of the companion’s gravity, which is the dominant factor in changing the envelope structure. The mixing length at the position of the companion can be larger than the local radius, implying a breakdown of mixing-length theory and suggesting the need for more turbulence in this region. The modified TPAGB star is more stable than the canonical TPAGB star and the CE density around the companion is significantly higher than that assumed in the original CEW model. Conclusions. Future work will require the modelling of systems with lower envelope masses and the inclusion of hydrodynamical effects during the CE phase.

WD+AGB star systems as the progenitors of type Ia supernovae

2018 ◽  
Vol 14 (S343) ◽  
pp. 540-541
Author(s):  
Bo Wang
Keyword(s):  
Type Ia Supernovae ◽  
Population Synthesis ◽  
Final Phase ◽  
Common Envelope ◽  
The Core ◽  
Delay Times ◽  
Careful Treatment ◽  
Type Ia ◽  
Ia Supernovae ◽  
Synthesis Approach

AbstractWD+AGB star systems have been suggested as an alternative way for producing type Ia supernovae (SNe Ia), known as the core-degenerate (CD) scenario. In the CD scenario, SNe Ia are produced at the final phase during the evolution of common-envelope through a merger between a carbon-oxygen (CO) WD and the CO core of an AGB secondary. However, the rates of SNe Ia from this scenario are still uncertain. In this work, I carried out a detailed investigation on the CD scenario based on a binary population synthesis approach. I found that the Galactic rates of SNe Ia from this scenario are not more than 20% of total SNe Ia due to more careful treatment of mass transfer, and that their delay times are in the range of ∼90 − 2500 Myr, mainly contributing to the observed SNe Ia with short and intermediate delay times.

scholarly journals Type Ia supernovae from non-accreting progenitors

2020 ◽  
Vol 635 ◽  
pp. A72 ◽  
Author(s):  
J. Antoniadis ◽  
S. Chanlaridis ◽  
G. Gräfener ◽  
N. Langer
Keyword(s):  
Nuclear Energy ◽  
Mass Range ◽  
Type Ia Supernovae ◽  
Core Collapse ◽  
Star Forming ◽  
Helium Stars ◽  
Type Ia ◽  
Complete Disruption ◽  
Ia Supernovae ◽  
Thermonuclear Runaway

Type Ia supernovae (SNe Ia) are manifestations of stars that are deficient in hydrogen and helium, and disrupt in a thermonuclear runaway. While explosions of carbon-oxygen white dwarfs are thought to account for the majority of events, part of the observed diversity may be due to varied progenitor channels. We demonstrate that helium stars with masses between ∼1.8 and 2.5 M⊙ may evolve into highly degenerate cores with near-Chandrasekhar mass and helium-free envelopes that subsequently ignite carbon and oxygen explosively at densities of ∼(1.8−5.9) × 109 g cm−3. This occurs either due to core growth from shell burning (when the core has a hybrid CO/NeO composition), or following ignition of residual carbon triggered by exothermic electron captures on 24Mg (for a NeOMg-dominated composition). We argue that the resulting thermonuclear runaway is likely to prevent core collapse, leading to the complete disruption of the star. The available nuclear energy at the onset of explosive oxygen burning suffices to create ejecta with a kinetic energy of ∼1051 erg, as in typical SNe Ia. Conversely, if these runaways result in partial disruptions, the corresponding transients would resemble SN Iax events similar to SN 2002cx. If helium stars in this mass range indeed explode as SNe Ia, then the frequency of events would be comparable to the observed SN Ib/c rates, thereby sufficing to account for the majority of SNe Ia in star-forming galaxies.

scholarly journals Sub-Chandrasekhar-mass detonations are in tension with the observed t0−MNi56 relation of type Ia supernovae

2020 ◽  
Vol 499 (4) ◽  
pp. 4725-4747
Author(s):  
Doron Kushnir ◽  
Nahliel Wygoda ◽  
Amir Sharon
Keyword(s):  
White Dwarf ◽  
Numerical Scheme ◽  
Radiation Transfer ◽  
Type Ia Supernovae ◽  
Escape Time ◽  
The Core ◽  
Type Ia ◽  
Γ Rays ◽  
Ia Supernovae ◽  
Detonation Model

ABSTRACT Type Ia supernovae (SNe Ia) are likely the thermonuclear explosions of carbon–oxygen (CO) white-dwarf (WD) stars, but their progenitor systems remain elusive. Recent studies have suggested that a propagating detonation within a thin helium shell surrounding a sub-Chandrasekhar mass CO core can subsequently trigger a detonation within the core (the double-detonation model, DDM). The outcome of this explosion is similar to a central ignition of a sub-Chandrasekhar mass CO WD (SCD). While SCD is consistent with some observational properties of SNe Ia, several computational challenges prohibit a robust comparison to the observations. We focus on the observed t0−MNi56 relation, where t0 (the γ-rays’ escape time from the ejecta) is positively correlated with MNi56 (the synthesized 56Ni mass). We apply our recently developed numerical scheme to calculate SCD and show that the calculated t0−MNi56 relation, which does not require radiation transfer calculations, converges to an accuracy of a few per cent. We find a clear tension between our calculations and the observed t0−MNi56 relation. SCD predicts an anticorrelation between t0 and MNi56, with $t_0\approx 30\, \textrm{d}$ for luminous ($M_\text{Ni56}\gtrsim 0.5\, \mathrm{ M}_{\odot }$) SNe Ia, while the observed t0 is in the range of $35\!-\!45\, \textrm{d}$. We show that this tension is larger than the uncertainty of the results, and that it exists in all previous studies of the problem. Our results hint that more complicated models are required, but we argue that DDM is unlikely to resolve the tension with the observations.

scholarly journals Thermonuclear explosion of a massive hybrid HeCO white-dwarf triggered by a He-detonation on a companion

2021 ◽  
Author(s):  
R Pakmor ◽  
Y Zenati ◽  
H B Perets ◽  
S Toonen
Keyword(s):  
Stellar Evolution ◽  
Two Dimensions ◽  
Type Ia Supernovae ◽  
Normal Type ◽  
The Core ◽  
Thermonuclear Explosion ◽  
Self Consistent ◽  
Type Ia ◽  
Ia Supernovae ◽  
Secondary Carbon

Abstract Normal type Ia supernovae (SNe) are thought to arise from the thermonuclear explosion of massive (>0.8 M⊙) carbon-oxygen white dwarfs (WDs), although the exact mechanism is debated. In some models helium accretion on to a carbon-oxygen (CO) WD from a companion was suggested to dynamically trigger a detonation of the accreted helium shell. The helium detonation then produces a shock that after converging on itself close to the core of the CO-WD, triggers a secondary carbon detonation and gives rise to an energetic explosion. However, most studies of such scenarios have been done in one or two dimensions, and/or did not consider self-consistent models for the accretion and the He-donor. Here we make use of detailed 3D simulation to study the interaction of a He-rich hybrid 0.69 M⊙ HeCO WD with a more massive 0.8 M⊙ CO WD. We find that accretion from the hybrid WD on to the CO WD gives rise to a helium detonation. However, the helium detonation does not trigger a carbon detonation in the CO WD. Instead, the helium detonation burns through the accretion stream to also burn the helium shell of the donor hybrid HeCO-WD. The detonation of its massive helium shell then compresses its CO core, and triggers its detonation and full destruction. The explosion gives rise to a faint, likely highly reddened transient, potentially observable by the Vera Rubin survey, and the high-velocity (∼1000 kms−1) ejection of the heated surviving CO WD companion. Pending on uncertainties in stellar evolution we estimate the rate of such transient to be up to $\sim 10{{\ \rm per\ cent}}$ of the rate of type Ia SNe.

The common-envelope wind model for type Ia supernovae

2018 ◽  
Vol 14 (S343) ◽  
pp. 470-471
Author(s):  
Xiangcun Meng ◽  
Philipp. Podsiadlowski
Keyword(s):  
Transfer Rate ◽  
Accretion Rate ◽  
Mass Transfer Rate ◽  
Type Ia Supernovae ◽  
Wind Model ◽  
Common Envelope ◽  
Type Ia ◽  
The Common ◽  
Ia Supernovae ◽  
Hybrid Carbon

AbstractWe have developed a new version of the SD model for type Ia supernovae (SNe Ia) in which a common envelope (CE) is assumed to form if the mass-transfer rate between a carbon/oxygen white dwarf (CO WD) and its companion exceeds a critical accretion rate. Based on this model, we found that both SN 2002cx-like and SN Ia-CSM objects may share a similar origin, i.e. these peculiar objects may originate from the explosion of hybrid carbon/oxygen/neon white dwarfs (CONe WDs) in SD systems, where SNe Ia-CSM explode in systems with a massive CE of ∼1 M⊙, while SN 2002cx-like events correspond to events without a massive CE.

scholarly journals Distances with <4% precision from type Ia supernovae in young star-forming environments

Science ◽  
2015 ◽  
Vol 347 (6229) ◽  
pp. 1459-1462 ◽  
Author(s):  
P. L. Kelly ◽  
A. V. Filippenko ◽  
D. L. Burke ◽  
M. Hicken ◽  
M. Ganeshalingam ◽  
...  
Keyword(s):  
Young Star ◽  
Type Ia Supernovae ◽  
Star Forming ◽  
Type Ia ◽  
Ia Supernovae
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