Title: SN Ia Explosions from Hybrid Carbon–Oxygen–Neon White Dwarf Progenitors that Have Mixed during Cooling

Abstract

The creation of“hybrid” white dwarfs, made of a C–O core within an O–Ne shell has been proposed, and earlier studies indicate that ignition in the C-rich central region makes these viable progenitors for thermonuclear(type Ia) supernovae. Recent work found that the C–O core is mixed with the surrounding O–Ne as the white dwarf cools prior to accretion, which results in lower central C fractions in the massive progenitor than previously assumed. To further investigate the efficacy of hybrid white dwarfs as progenitors of thermonuclear supernovae, we performed simulations of thermonuclear supernovae from a new series of hybrid progenitors that include the effects of mixing during cooling. The progenitor white dwarf model was constructed with the one-dimensional stellar evolution code Modules for Experiments in Stellar Astrophysics (MESA) and represented a star evolved through the phase of unstable interior mixing followed by accretion until it reached conditions for the ignition of carbon burning. This MESA model was then mapped to a two-dimensional initial condition for explosions simulated with FLASH. For comparison, similar simulations were performed for a traditional C–O progenitor white dwarf. By comparing the yields of the explosions, we find that, as with earlier studies, the lower C abundance in themore » hybrid progenitor compared to the traditional C–O progenitor leads to a lower average yield of ⁵⁶Ni. Although the unmixed hybrid white dwarf showed a similar decrement also in total iron-group yield, the mixed case does not and produces a smaller fraction of iron-group elements in the form of ⁵⁶Ni. We attribute this to the higher central density require for ignition and the location, center or off-center, of deflagration ignition.« less

Authors:

Augustine, Carlyn N.  ^[1];

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Willcox, Donald E.  ^[2];

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Brooks, Jared ^[3]; Townsley, Dean M.  ^[1];

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Calder, Alan C.  ^[4]

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• Search DOE PAGES for ORCID "0000-0001-5525-089X"
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+ Show Author Affiliations

1. Univ. of Alabama, Tuscaloosa, AL (United States)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
3. Univ. of California, Santa Barbara, CA (United States)
4. Stony Brook Univ., NY (United States)

Publication Date:

2019-12-18

Research Org.:

Stony Brook Univ., NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); National Science Foundation (NSF)

OSTI Identifier:

1593806

Report Number(s):

arXiv:1910.12403v1
Journal ID: ISSN 1538-4357

Grant/Contract Number:  

FG02-87ER40317; AST-1211563

Resource Type:

Accepted Manuscript

Journal Name:

The Astrophysical Journal (Online)

Additional Journal Information:

Journal Name: The Astrophysical Journal (Online); Journal Volume: 887; Journal Issue: 2; Journal ID: ISSN 1538-4357

Publisher:

Institute of Physics (IOP)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; Explosive nucleosynthesis; Type Ia supernovae; Hydrodynamical simulations; White dwarf stars