Formation and evolution of hybrid He–CO white dwarfs and their properties

Zenati, Yossef; Toonen, Silvia; Perets, Hagai B.

doi:10.1093/mnras/sty2723

Cited by 75 publications

(101 citation statements)

References 50 publications

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“…Alternatively, the white dwarfs in SDSS J1152+0248 may have hybrid helium-carbon-oxygen cores, which have radii similar to carbon-oxygen core white dwarfs 17 . It is also possible that these are helium-core white dwarfs with extremely thin surface hydrogen layers (M H /M * < 10 −8 ), although producing such a thin surface layer is difficult 33 .…”

Section: Discussionmentioning

confidence: 99%

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A pulsating white dwarf in an eclipsing binary

et al. 2020

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White dwarfs are the burnt out cores of Sun-like stars and are the final fate of 97% of all stars in our Galaxy. The internal structure and composition of white dwarfs are hidden by their high gravities, which causes all elements, apart from the lightest ones, to settle out of their atmospheres. The most direct method to probe the inner structure of stars and white dwarfs in detail is via asteroseismology. Here we present the first known pulsating white dwarf in an eclipsing binary system, enabling us to place extremely precise constraints on the mass and radius of the white dwarf from the light curve, independent of the pulsations. This 0.325 M white dwarf -one member of SDSS J115219.99+024814.4 -will serve as a powerful benchmark to constrain empirically the core composition of low-mass stellar remnants and investigate the effects of close binary evolution on the internal structure of white dwarfs.

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Section: Discussionmentioning

confidence: 99%

“…The theoretical models have the same temperatures as the white dwarfs in SDSS J1152+0248 (the shaded regions account for the uncertainty in the measured temperatures). It is also possible that these are both hybrid helium-carbon-oxygen core white dwarfs (which sit between the different models 17 ).…”

Section: The Radial Velocity Fitting Methodsmentioning

confidence: 99%

A pulsating white dwarf in an eclipsing binary

et al. 2020

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“…The former are the outcomes of regular evolution of single stars, which results in WDs composed of ∼50 % carbon and ∼50 % oxygen. The hybrid WDs, containing both CO and He, are the outcomes of binary stellar evolution, as described in Zenati et al (2018). Subsequently, we used these stellar profiles to set up our WD models in FLASH and SPH codes.…”

Section: The Neutron Star and White Dwarf Modelsmentioning

confidence: 99%

Faint rapid red transients from neutron star–CO white dwarf mergers

Zenati

Bobrick

Perets

2020

Monthly Notices of the Royal Astronomical Society

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Mergers of neutron stars (NS) and white dwarfs (WD) may give rise to observable explosive transient events. We use 3D hydrodynamical (SPH) simulations, as well as 2D hydrodynamical-thermonuclear simulations (using the FLASH AMR code) to model the disruption of CO-WDs by NSs, which produce faint transient events. We postprocess the simulations using a large nuclear network and make use of the SuperNu radiation-transfer code to predict the observational signatures and detailed properties of these transients. We calculate the light-curves (LC) and spectra for five models of NS -CO-WD mergers. The small yields of 56 Ni (few×10 −3 M ) result in faint, rapidly-evolving reddened transients (RRTs) with B (R) -peak magnitudes of ∼ −12 (−13) to ∼ −13 (−15), much shorter and fainter than both regular and faint/peculiar type-Ia SNe. We show that the spectra of RRTs share some similarities with rapidlyevolving transients such as SN2010x, though RRTs are significantly fainter, especially in the I/R bands, and show far stronger Si lines. We estimate that the upcoming Large Synoptic Survey Telescope could detect RRTs at a rate of ∼ 10 − 70 yr −1 , through observations in the R/I bands.

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“…Our study does show that the DD scenario can best account for the early excess emission of SN 2018oh. The DD scenario might be the main sub-Chandrasekhar SN scenario (e.g., Maoz et al 2014), including many WD-WD mergers from the hybrid channel, i.e., at least one of the WDs is a carbon-oxygen WD with large helium content (e.g., Zenati et al 2019). We look forward to the continuation of high cadence surveys with detection near first light and additional observations of unique early light curve behaviour -perhaps not so unique after all.…”

Section: Discussionmentioning

confidence: 99%

Explaining the Early Excess Emission of the Type Ia Supernova 2018oh by the Interaction of the Ejecta with Disk-originated Matter

Levanon

Soker

2019

ApJL

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We explain the early excess emission of the Type Ia supernova 2018oh by an interaction of the supernova ejecta with disk-originated matter (DOM). Such DOM can form in the merger process of two white dwarfs (WDs) in the double degenerate scenario of Type Ia supernovae (SNe Ia). We find that an ejecta-DOM interaction can fit the early light curve of SN 2018oh better than an ejecta-companion interaction in the single degenerate scenario. By composing the DOM from two components that were ejected in the merger process with two different velocities, we show that the ejecta-DOM interaction can account for the linear rise in the light curve, while the ejecta-companion interaction predicts too steep a rise. In addition, the ejecta-DOM interaction does not predict the presence of hydrogen and helium lines in nebular spectra, and hence does not suffer from this major drawback of the ejectacompanion model. We consider the ejecta-DOM interaction to be the most likely explanation for the early excess emission in SN 2018oh. By that we show that the double degenerate scenario can account for early excess emission in SNe Ia. arXiv:1812.05054v3 [astro-ph.HE]

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Formation and evolution of hybrid He–CO white dwarfs and their properties

Cited by 75 publications

References 50 publications

A pulsating white dwarf in an eclipsing binary

A pulsating white dwarf in an eclipsing binary

Faint rapid red transients from neutron star–CO white dwarf mergers

Explaining the Early Excess Emission of the Type Ia Supernova 2018oh by the Interaction of the Ejecta with Disk-originated Matter

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