Recurrent novae: Single degenerate progenitors of Type Ia supernovae
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J. Astrophys. Astr. (2020) 41:43 https://doi.org/10.1007/s12036-020-09661-8
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Recurrent novae: Single degenerate progenitors of Type Ia supernovae G. C. ANUPAMA*
and M. PAVANA
Indian Institute of Astrophysics, II Block Koramangala, Bengaluru 560 034, India. *Corresponding author. E-mail: [email protected] MS received 15 September 2020; accepted 19 October 2020 Abstract. Type Ia supernovae are the result of explosive thermonuclear burning in CO white dwarfs. The progenitors of the Ia supernovae are white dwarfs in an interacting binary system. The donor companion is either a degenerate star (white dwarf) or a non-degenerate star (e.g. red giant). Recurrent novae are interacting binaries with a massive white dwarf accreting from either a main sequence, slightly evolved, or a red giant star. The white dwarf in these systems is a massive, hot white dwarf, accreting at a high rate. Recurrent novae are thought to be the most promising single degenerate progenitors of Type Ia supernovae. Presented here are the properties of a few recurrent novae based on recent outbursts. The elemental abundances and their distribution in the ejected shell are discussed. Keywords. Type Ia supernovae—recurrent novae—abundances.
1. Introduction 1.1 Type Ia supernovae Type Ia supernovae (SNe Ia) are the result of explosive thermonuclear burning in CO white dwarfs (WDs). The outcome of the explosive CO fusion leads to an ejecta structure in which iron group elements (IGE), including 56 Ni, make up the inner regions, surrounded by Si-rich outer layers. The distinguishing feature of SNe Ia spectra is the lack of hydrogen features, and the prominent Si II absorption features at maximum. The peak luminosity is dependent on the amount of 56 Ni synthesised during the explosion and the rate of decline is correlated with the peak luminosity, with brighter slower and fainter faster events (Phillips 1993). This correlation makes SNe Ia good standardizable candles for cosmology. In addition, SNe Ia are responsible for more than half the iron in the Solar neighbourhood (Maoz & Graur 2017).
This article is part of the Topical Collection: Chemical elements in the Universe: Origin and evolution.
Diversity in SNe Ia has become apparent in recent times with the increase in the discovery and detailed studies of these objects. It is found that nearly 30% of the events do not follow the Phillips relation. The diversity in the observed properties have given rise to the possibilities of (a) different mechanisms for the explosion, and (b) different progenitors. Theoretical modelling, combined with observational data, indicate the likely scenarios for the explosion are the delayed detonation (deflagration-to-detonation) of a Chandrasekhar mass WD (Khokhlov 1991) where the propagating nuclear flame starts off as a subsonic deflagration and transitions to a supersonic detonation at a critical density; or a prompt detonation (doubledetonation) in a sub-Chandrasekhar mass WD (Woosley & Weaver 1994). The most promi
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