Asymmetry and the Nucleosynthetic Signature of Nearly Edge-Lit Detonation in White Dwarf Cores

Chamulak, David A.; Seitenzahl, Ivo R.; Truran, J. W.

doi:10.1088/0004-637x/744/1/27

Cited by 15 publications

(13 citation statements)

References 34 publications

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“…A series of observational studies makes it clear that both the environment and the path that lead to SNe Ia explosions play a role in their yields (e.g., Stritzinger et al 2006;Ellis et al 2008;Howell et al 2009;Kelly et al 2010;Foley et al 2013;Graham et al 2015). These results corroborate the outcomes of several theoretical models suggesting that the SNe Ia yields are strongly affected by the metallicity, mass, and age of the progenitor (e.g., Timmes et al 2003;Travaglio et al 2005Travaglio et al , 2015Mannucci et al 2006;Jackson et al 2010;De et al 2014) and by asymmetries in the explosion (Chamulak et al 2012).…”

Section: Evolution Of the [X/fe] Ratiossupporting

confidence: 89%

Nucleosynthetic history of elements in the Galactic disk

Spina

Meléndez

Karakas

et al. 2016

A&A

131

217

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Context. The chemical composition of stars is intimately linked to the formation and evolution of the Galaxy. Aims. We aim to trace the chemical evolution of the Galactic disk through the inspection of the [X/Fe]-age relations of 24 species from C to Eu. Methods. Using high-resolution and high signal-to-noise UVES spectra of nine solar twins, we obtained precise estimates of stellar ages and chemical abundances. These determinations have been integrated with additional accurate age and abundance determinations from recent spectroscopic studies of solar twins existing in the literature, comprising superb abundances with 0.01 dex precision. Based on this data set, we outlined the [X/Fe]-age relations over a time interval of 10 Gyr. Results. We present the [X/Fe]-age relations for 24 elements (C, O,

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Section: Evolution Of the [X/fe] Ratiossupporting

confidence: 89%

Nucleosynthetic history of elements in the Galactic disk

Spina

Meléndez

Karakas

et al. 2016

A&A

131

217

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“…the S‐model studied here rather than those of Fink et al 2010 and Kromer et al 2010) since the difference between the CSDD and ELDD mechanisms will be largest in this case (see ). However, it does have some relevance to the study of more massive cores since the position of an off‐centre ignition imprints distinctive signatures on the explosion ejecta (Chamulak et al 2011).…”

Section: Discussionmentioning

confidence: 99%

2D simulations of the double-detonation model for thermonuclear transients from low-mass carbon-oxygen white dwarfs

Sim

Fink

Kromer

et al. 2012

Monthly Notices of the Royal Astronomical Society

152

250

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Thermonuclear explosions may arise in binary star systems in which a carbon-oxygen (CO) white dwarf (WD) accretes helium-rich material from a companion star. If the accretion rate allows a sufficiently large mass of helium to accumulate prior to ignition of nuclear burning, the helium surface layer may detonate, giving rise to an astrophysical transient. Detonation of the accreted helium layer generates shock waves that propagate into the underlying CO WD. This might directly ignite a detonation of the CO WD at its surface (an edge-lit secondary detonation) or compress the core of the WD sufficiently to trigger a CO detonation near the centre. If either of these ignition mechanisms works, the two detonations (helium and CO) can then release sufficient energy to completely unbind the WD. These 'double-detonation' scenarios for thermonuclear explosion of WDs have previously been investigated as a potential channel for the production of Type Ia supernovae from WDs of ∼1 M . Here we extend our 2D studies of the double-detonation model to significantly less massive CO WDs, the explosion of which could produce fainter, more rapidly evolving transients. We investigate the feasibility of triggering a secondary core detonation by shock convergence in low-mass CO WDs and the observable consequences of such a detonation. Our results suggest that core detonation is probable, even for the lowest CO core masses that are likely to be realized in nature. To quantify the observable signatures of core detonation, we compute spectra and light curves for models in which either an edge-lit or compression-triggered CO detonation is assumed to occur. We compare these to synthetic observables for models in which no CO detonation was allowed to occur. If significant shock compression of the CO WD occurs prior to detonation, explosion of the CO WD can produce a sufficiently large mass of radioactive iron-group nuclei to significantly affect the light curves. In particular, this can lead to relatively slow post-maximum decline. If the secondary detonation is edge-lit, however, the CO WD explosion primarily yields intermediate-mass elements that affect the observables more subtly. In this case, near-infrared observations and detailed spectroscopic analysis would be needed to determine whether a core detonation occurred. We comment on the implications of our results for understanding peculiar astrophysical transients including SN 2002bj, SN 2010X and SN 2005E.

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“…We note the asymmetry of the model, with the ejecta in the upper hemisphere extending to much higher velocities. This asymmetric extent of the ejecta in velocity space is a natural consequence of the single spot near-surface lit detonation (Chamulak et al 2012). …”

Section: Nucleosynthesismentioning

confidence: 99%

Three-dimensional simulations of gravitationally confined detonations compared to observations of SN 1991T

Seitenzahl

Kromer

Ohlmann

et al. 2016

A&A

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The gravitationally confined detonation (GCD) model has been proposed as a possible explosion mechanism for Type Ia supernovae in the single-degenerate evolution channel. It starts with ignition of a deflagration in a single off-centre bubble in a near-Chandrasekharmass white dwarf. Driven by buoyancy, the deflagration flame rises in a narrow cone towards the surface. For the most part, the main component of the flow of the expanding ashes remains radial, but upon reaching the outer, low-pressure layers of the white dwarf, an additional lateral component develops. This causes the deflagration ashes to converge again at the opposite side, where the compression heats fuel and a detonation may be launched. We first performed five three-dimensional hydrodynamic simulations of the deflagration phase in 1.4 M carbon/oxygen white dwarfs at intermediate-resolution (256 3 computational zones). We confirm that the closer the initial deflagration is ignited to the centre, the slower the buoyant rise and the longer the deflagration ashes takes to break out and close in on the opposite pole to collide. To test the GCD explosion model, we then performed a high-resolution (512 3 computational zones) simulation for a model with an ignition spot offset near the upper limit of what is still justifiable, 200 km. This high-resolution simulation met our deliberately optimistic detonation criteria, and we initiated a detonation. The detonation burned through the white dwarf and led to its complete disruption. For this model, we determined detailed nucleosynthetic yields by post-processing 10 6 tracer particles with a 384 nuclide reaction network, and we present multi-band light curves and time-dependent optical spectra. We find that our synthetic observables show a prominent viewing-angle sensitivity in ultraviolet and blue wavelength bands, which contradicts observed SNe Ia. The strong dependence on the viewing angle is caused by the asymmetric distribution of the deflagration ashes in the outer ejecta layers. Finally, we compared our model to SN 1991T. The overall flux level of the model is slightly too low, and the model predicts pre-maximum light spectral features due to Ca, S, and Si that are too strong. Furthermore, the model chemical abundance stratification qualitatively disagrees with recent abundance tomography results in two key areas: our model lacks low-velocity stable Fe and instead has copious amounts of high-velocity 56 Ni and stable Fe. We therefore do not find good agreement of the model with SN 1991T.

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Asymmetry and the Nucleosynthetic Signature of Nearly Edge-Lit Detonation in White Dwarf Cores

Cited by 15 publications

References 34 publications

Nucleosynthetic history of elements in the Galactic disk

Nucleosynthetic history of elements in the Galactic disk

2D simulations of the double-detonation model for thermonuclear transients from low-mass carbon-oxygen white dwarfs

Three-dimensional simulations of gravitationally confined detonations compared to observations of SN 1991T

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