He-shell flashes on the surface of oxygen-neon white dwarfs

Guo, Yunlang; Liu, Dongdong; Wu, Chenjie; Wang, Bo

doi:10.1088/1674-4527/21/2/34

Cited by 5 publications

(3 citation statements)

References 90 publications

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“…Mixing with different chemical substrates has also been reported in Casanova et al (2016Casanova et al ( , 2018. Guo et al (2021a) recently reproduced the chemical abundances in some novae with He enrichments by considering the He and WD mixing process. They found that the He mixing level in classical novae is lower than 30%.…”

Section: Introductionmentioning

confidence: 83%

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Mixing fraction in classical novae

Guo

Wang

2022

A&A

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Context. Classical novae are powered by thermonuclear runaways occurring on the surface of accreting white dwarfs (WDs). In the observations, the enrichments of heavy elements in nova ejecta have been detected, indicating a mixing process between the accreted matter and the matter from the outer layers of the underlying WDs prior to nova outbursts. However, the mixing fraction in classical novae is still uncertain. Aims. The purpose of this article is to investigate some elemental abundance ratios during nova outbursts that can be used to estimate the WD mixing fraction in classical novae. Methods. By considering different WD mixing fractions with the stellar evolution code Modules for Experiments in Stellar Astrophysics, we carried out a series of simulations of nova outbursts, in which the initial CO WD masses range from 0.7−1.0 M⊙. Results. We identified four elemental abundance ratios (i.e. (H + He)/∑CNO, (H + He)/Ne, ∑CNO/Mg, and ∑CNO/Si) that satisfy the conditions for determining the WD mixing fraction, in which (H + He)/∑CNO is the most suitable mixing meter. We also estimated the WD mixing fraction in some representative classical novae. Additionally, we found that a higher metallicity (i.e. higher WD mixing fraction) is preferentially accompanied by a longer t2 (the time of decline by two magnitudes from peak luminosity) during nova outbursts. Our results can be used to constrain the mixing process in classical novae.

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Section: Introductionmentioning

confidence: 83%

“…We adopted the super-Eddington wind as the mass-loss mechanism during nova outbursts, in which the super-Eddington luminosity (L Edd ) and the wind mass-loss rate ( Ṁ) can be expressed as follows (e.g. Denissenkov et al 2012;Wang et al 2015;Wu et al 2017;Guo et al 2021a):…”

Section: Nova Modelsmentioning

confidence: 99%

Mixing fraction in classical novae

Guo

Wang

2022

A&A

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“…We adopted the super-Eddington wind as the mass loss mechanism during nova outbursts, in which the super-Eddington luminosity (L Edd ) and the wind mass-loss rate ( Ṁ) can be expressed as follows (e.g. Denissenkov et al 2013;Wang et al 2015;Wu et al 2017;Guo et al 2021a):…”

Section: Nova Modelsmentioning

confidence: 99%

Mixing fraction in classical novae

Guo,

Wu,

Wang

2022

Preprint

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Context. Classical novae are powered by thermonuclear runaways occurring on the surface of accreting white dwarfs (WDs). In the observations, the enrichments of heavy elements in nova ejecta have been detected, indicating the existence of a mixing process between the accreted matter and the matter from the outer layers of the underlying WDs prior to nova outbursts. However, the mixing fraction in classical novae is still uncertain.Aims. The purpose of this article is to investigate some elemental abundance ratios during nova outbursts, which can be used to estimate the WD-mixing fraction in classical novae. Methods. By considering different WD-mixing fractions with the stellar evolution code Modulesfor Experiments in Stellar Astrophysics (MESA), we carried out a series of simulations of nova outbursts, in which the initial CO WD masses range from 0.7 − 1.0 M ⊙ .Results. We identified four elemental abundance ratios (i.e. (H + He)/ CNO, (H + He)/Ne, CNO/Mg and CNO/Si) that satisfy the conditions for determining the WD-mixing fraction, in which (H + He)/ CNO is the most suitable mixing meter. We also estimated the WD-mixing fraction in some representative classical novae. Additionally, we found that a higher metallicity (i.e. higher WD-mixing fraction) prefers to be accompanied by a longer t 2 (the time of decline by two magnitudes from peak luminosity) during nova outbursts. The present results can be used to constrain the mixing process in classical novae.

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Helium enrichment during classical nova outbursts

Guo

Wang

2021

Monthly Notices of the Royal Astronomical Society

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Nova outbursts play an important role in the chemical evolution of galaxies, especially they are the main source of synthetic $^{13}\rm C$, $^{15}\rm N$, $^{17}\rm O$ and some radioactive isotopes like $^{22}\rm Na$ and $^{26}\rm Al$. The enrichment of He in nova ejecta indicates that the accreted material may mix with the He-shell (He-mixing). The purpose of this work is to investigate how the He-mixing affects the nova outbursts in a systematic way. We evolved a series of accreting WD models, and found that the mass fraction of H and He in nova ejecta can be influenced by different He-mixing fractions significantly. We also found that both the nova cycle duration and ejected mass increase with the He-mixing fractions. Meanwhile, the nuclear energy generation rate of p-p chains decreases with the He-mixing fraction during the nova outbursts, whereas the CNO-cycle increases. The present work can reproduce the chemical abundances in the ejecta of some representative novae, such as GQ Mus, ASASSN-18fv, HR Del, T Aur and V443 Sct. This implies that the He-mixing process cannot be neglected when studying nova outbursts. This study also develops a He-mixing meter (i.e. $\rm He/H$) that can be used to estimate the He-mixing fraction in classical nova systems.

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He-shell flashes on the surface of oxygen-neon white dwarfs

Cited by 5 publications

References 90 publications

Mixing fraction in classical novae

Mixing fraction in classical novae

Mixing fraction in classical novae

Helium enrichment during classical nova outbursts

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