The CO White Dwarf + Intermediate-mass/Massive Star Binary Evolution: Possible Merger Origins for Peculiar Type Ia and II Supernovae

ABSTRACT Supersoft X-ray sources (SSS) have been identified as white dwarfs accreting from binary companions and undergoing nuclear burning of the accreted material on their surface. Although expected to be a relatively numerous population from both binary evolution models and their identification as type Ia supernova progenitor candidates, given the very soft spectrum of SSSs relatively few are known. Here we report on the X-ray and optical properties of 1RXS J050526.3−684628, a previously unidentified accreting nuclear-burning white dwarf located in the Large Magellanic Cloud (LMC). XMM–Newton observations enabled us to study its X-ray spectrum and measure for the first time short-period oscillations of ∼170 s. By analysing newly obtained X-ray data by eROSITA, together with Swift observations and archival ROSAT data, we have followed its long-term evolution over the last 3 decades. We identify 1RXS J050526.3−684628 as a slowly evolving post-nova SSS undergoing residual surface nuclear burning, which finally reached its peak in 2013 and is now declining. Though long expected on theoretical grounds, such long-lived residual-burning objects had not yet been found. By comparison with existing models, we find that the effective temperature and luminosity evolution are consistent with an ∼0.7 M⊙ carbon–oxygen white dwarf accreting ${\sim} 10^{-9}~\rm {M}_{\odot }$ yr−1. Our results suggest that there may be many more undiscovered SSSs and ‘missed’ novae awaiting dedicated deep X-ray searches in the LMC and elsewhere.

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Pre-explosion Properties of Helium Star Donors to Thermonuclear Supernovae

The Astrophysical Journal ◽

10.3847/1538-4357/ac27ae ◽

2021 ◽

Vol 922 (2) ◽

pp. 241

Author(s):

Tin Long Sunny Wong ◽

Josiah Schwab ◽

Ylva Götberg

Keyword(s):

Stellar Evolution ◽

White Dwarf ◽

Stellar Atmosphere ◽

Thermonuclear Supernovae ◽

Atmosphere Model ◽

Binary Evolution ◽

Star Binary ◽

Helium Star

Abstract Helium star–carbon-oxygen white dwarf (CO WD) binaries are potential single-degenerate progenitor systems of thermonuclear supernovae. Revisiting a set of binary evolution calculations using the stellar evolution code MESA, we refine our previous predictions about which systems can lead to a thermonuclear supernova and then characterize the properties of the helium star donor at the time of explosion. We convert these model properties to near-UV/optical magnitudes assuming a blackbody spectrum and support this approach using a matched stellar atmosphere model. These models will be valuable to compare with pre-explosion imaging for future supernovae, though we emphasize the observational difficulty of detecting extremely blue companions. The pre-explosion source detected in association with SN 2012Z has been interpreted as a helium star binary containing an initially ultra-massive WD in a multiday orbit. However, extending our binary models to initial CO WD masses of up to 1.2 M ⊙, we find that these systems undergo off-center carbon ignitions and thus are not expected to produce thermonuclear supernovae. This tension suggests that, if SN 2012Z is associated with a helium star–WD binary, then the pre-explosion optical light from the system must be significantly modified by the binary environment and/or the WD does not have a carbon-rich interior composition.

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Close Binary White Dwarfs and Supernovae la

International Astronomical Union Colloquium ◽

10.1017/s0252921100152121 ◽

2004 ◽

Vol 194 ◽

pp. 113-116

Author(s):

R. Napiwotzki ◽

C. Karl ◽

G. Nelemans ◽

L. Yungelson ◽

N. Christlieb ◽

...

Keyword(s):

Radial Velocity ◽

White Dwarf ◽

White Dwarfs ◽

Close Binary ◽

Current Status ◽

Large Sample ◽

Observational Test ◽

Type Ia ◽

Binary Evolution

AbstractWe report on the current status of radial velocity surveys for white dwarf binaries (double degenerates DDs) including SPY (ESO Supernovae la progenitor survey) recently carried out at the VLT. A large sample of DD will allow us to put strong constraints on the phases of close binary evolution of the progenitor systems and to perform an observational test of the DD scenario for Supernovae of type Ia.

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Two delays in white dwarf evolution revealed by Gaia

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320000460 ◽

2019 ◽

Vol 15 (S357) ◽

pp. 175-178

Author(s):

Sihao Cheng

Keyword(s):

White Dwarf ◽

White Dwarfs ◽

The Other ◽

High Mass ◽

Type Ia Supernovae ◽

Type Ia ◽

Two Delays ◽

Binary Evolution ◽

Ia Supernovae

AbstractBy comparing two age indicators of high-mass white dwarfs (WDs) derived from Gaia data, two discoveries have been made recently: one is the existence of a cooling anomaly that produces the Q branch structure on the Hertzsprung–Russell diagram, and the other is the existence of high-mass WDs as double-WD merger products. The former poses a challenge for WD cooling models, and the latter has implications on binary evolution and type-Ia supernovae.

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The Formation and Evolution of Very Massive Stars in Dense Stellar Systems

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308015925 ◽

2007 ◽

Vol 3 (S246) ◽

pp. 357-358

Author(s):

Houria Belkus ◽

Joris Van Bever ◽

Dany Vanbeveren

Keyword(s):

Black Holes ◽

Massive Star ◽

Massive Stars ◽

Stellar Systems ◽

Intermediate Mass ◽

Single Star ◽

Evolutionary Scheme ◽

Stellar Collisions ◽

Formation And Evolution ◽

Binary Evolution

AbstractThe early evolution of dense stellar systems is governed by massive single star and binary evolution. Core collapse of dense massive star clusters can lead to the formation of very massive objects through stellar collisions (M≥ 1000M⊙). Stellar wind mass loss determines the evolution and final fate of these objects, and determines whether they form black holes (with stellar or intermediate mass) or explode as pair instability supernovae, leaving no remnant. We present a computationally inexpensive evolutionary scheme for very massive stars that can readily be implemented in an N-body code. Using our new N-body code ‘Youngbody’ which includes a detailed treatment of massive stars as well as this new scheme for very massive stars, we discuss the formation of intermediate mass and stellar mass black holes in young starburst regions. A more detailed account of these results can be found in Belkus, Van Bever & Vanbeveren (2007).

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The effects of different Type Ia SN yields on Milky Way chemical evolution

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab293 ◽

2021 ◽

Vol 503 (3) ◽

pp. 3216-3231

Author(s):

Marco Palla

Keyword(s):

Chemical Evolution ◽

White Dwarf ◽

Time Distribution ◽

Milky Way ◽

Massive Stars ◽

Abundance Patterns ◽

Type Ia ◽

Low Metallicity ◽

Explosion Mechanism ◽

Chemical Evolution Model

ABSTRACT We study the effect of different Type Ia SN nucleosynthesis prescriptions on the Milky Way chemical evolution. To this aim, we run detailed one-infall and two-infall chemical evolution models, adopting a large compilation of yield sets corresponding to different white dwarf progenitors (near-Chandrasekar and sub-Chandrasekar) taken from the literature. We adopt a fixed delay time distribution function for Type Ia SNe, in order to avoid degeneracies in the analysis of the different nucleosynthesis channels. We also combine yields for different Type Ia SN progenitors in order to test the contribution to chemical evolution of different Type Ia SN channels. The results of the models are compared with recent LTE and NLTE observational data. We find that ‘classical’ W7 and WDD2 models produce Fe masses and [α/Fe] abundance patterns similar to more recent and physical near-Chandrasekar and sub-Chandrasekar models. For Fe-peak elements, we find that the results strongly depend either on the white dwarf explosion mechanism (deflagration-to-detonation, pure deflagration, double detonation) or on the initial white dwarf conditions (central density, explosion pattern). The comparison of chemical evolution model results with observations suggests that a combination of near-Chandrasekar and sub-Chandrasekar yields is necessary to reproduce the data of V, Cr, Mn and Ni, with different fractions depending on the adopted massive stars stellar yields. This comparison also suggests that NLTE and singly ionized abundances should be definitely preferred when dealing with most of Fe-peak elements at low metallicity.

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