An unusual white dwarf star may be a surviving remnant of a subluminous Type Ia supernova

Vennes, S.; Németh, P.; Kawka, A.; Thorstensen, J. R.; Khalack, V.; Ferrario, Lilia; Alper, Erek

doi:10.1126/science.aam8378

Cited by 88 publications

(133 citation statements)

References 46 publications

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“…After their initial phase of radius expansion, the remnants from model 2 cool and contract as low-mass WDs incapable of any further nuclear burning. model 2 can evolve near the locations on the HR diagram for GD 492 (LP 40-365) and J1603-6613 (Vennes et al 2017;Raddi et al 2018aRaddi et al ,b, 2019, and remain there for the 10 6 -10 7 years expected from their kinematics and location in the galaxy. The ejection velocities for our models are somewhat higher than the ≈600 km/s inferred by Raddi et al (2018aRaddi et al ( , 2019 for these objects when accounting for the rotation velocity of the galactic disk.…”

Section: Post-interaction Evolution With Mesamentioning

confidence: 92%

Remnants of Subdwarf Helium Donor Stars Ejected from Close Binaries with Thermonuclear Supernovae

Bauer

White

Bildsten

2019

ApJ

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Some binary systems composed of a white dwarf (WD) and a hot sub-dwarf (sdB) helium star will make contact within the helium burning lifetime of the sdB star at orbital periods of 20-30 minutes. The accreted helium on the WD inevitably undergoes a thermonuclear instability, causing a detonation that is expected to transition into the WD core and lead to a thermonuclear supernova. The short orbital period at this moment implies donor orbital velocities of 700-900 km/s. Motivated by the recent discovery of objects moving at these velocities and occupying unusual locations on the HR diagram, we explore the impact of the thermonuclear supernovae on the donors in this specific double detonation scenario. We use MESA to model the binary up to the moment of detonation, then 3D Athena++ to model the hydrodynamic interaction of the supernova ejecta with the donor star, calculating the amount of mass that is stripped and the entropy deposited in the deep stellar interior by the strong shock that traverses it. Receiving little additional momentum from the ejecta, we show that these donor remnants are simply ejected with velocities set by their original orbital speeds: 700-900 km/s. We model the long-term thermal evolution of remnants by introducing the shock entropy into MESA models. In response to this entropy change, donor remnants expand and brighten for timescales ranging from 10 6 -10 8 years, giving ample time for these runaway stars to be observed in their inflated state before they leave the galaxy. Even after surface layers are stripped, some donors retain enough mass to resume core helium burning and further delay fading for more than 10 8 years.

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Section: Post-interaction Evolution With Mesamentioning

confidence: 92%

Remnants of Subdwarf Helium Donor Stars Ejected from Close Binaries with Thermonuclear Supernovae

Bauer

White

Bildsten

2019

ApJ

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“…It is possible this explosion does not completely disrupt the white dwarf, leaving a bound remnant 149 . Surviving examples of such incomplete explosions may have been discovered in our Galaxy as fast-moving white dwarfs with unusual abundances 150,151 .…”

Section: The Thermonuclear Supernova Zoomentioning

confidence: 99%

Observational properties of thermonuclear supernovae

2019

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The explosive death of a star as a supernova is one of the most dramatic events in the Universe. Supernovae have an outsized impact on many areas of astrophysics: they are major contributors to the chemical enrichment of the cosmos and significantly influence the formation of subsequent generations of stars and the evolution of galaxies. Here we review the observational properties of thermonuclear supernovae, exploding white dwarf stars resulting from the stellar evolution of low-mass stars in close binary systems. The best known objects in this class are type Ia supernovae (SN Ia), astrophysically important in their application as standardisable candles to measure cosmological distances and the primary source of iron group elements in the Universe. Surprisingly, given their prominent role, SN Ia progenitor systems and explosion mechanisms are not fully understood; the observations we describe here provide constraints on models, not always in consistent ways. Recent advances in supernova discovery and follow-up have shown that the class of thermonuclear supernovae includes more than just SN Ia, and we characterise that diversity in this review.The modern classification scheme for supernovae traces back to Minkowski 1 who in 1941 split "Type I" from "Type II" supernovae based on optical spectra. Further subdivision of these basic classes has continued on an empirical basis 2, 3 , and in our review we describe the observational properties of what are now called SN Ia, along with other similar objects. The observational classification effort arises from a desire for physical understanding of these objects, explaining our use of the term thermonuclear supernovae in the title. That categorisation is based on the explosion mechanism: objects where the energy released in the explosion is primarily the result of thermonuclear fusion. Given our current state of knowledge, we could equally well call this a review of the observational properties of white dwarf supernovae, a categorisation based on the kind of object that explodes. This is contrasted with core-collapse or massive star supernovae, respectively, in the explosion mechanism or exploding object categorisations. Unlike those objects, where clear observational evidence exists for massive star progenitors and corecollapse (from both neutrino emission and remnant pulsars), the direct evidence for thermonuclear supernova explosions of white dwarfs is limited 4, 5 and not necessarily simply interpretable 6, 7 . Nevertheless, the indirect evidence is strong, though many open questions about the progenitor systems and explosion mechanisms remain.SN Ia are important both to the evolution of the Universe and to our understanding of it. As standardisable candles whose distance can be observationally inferred 8 , SN Ia have a starring role in the discovery of the accelerating expansion of the Universe 9, 10 and in measurement of its current expansion rate 11 . SN Ia are also major contributors to the chemical enrichment of the Universe, producing most of its iron 12 and elem...

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“…Recently,Kepler et al (2016a) identified a WD having an O-dominated atmosphere with traces of Ne and Mg, that could be the bare core of a Super-AGB star. Finally, another O-and Ne-rich WD but with a very low mass was discovered byVennes et al (2017).…”

mentioning

confidence: 95%

Pulsating white dwarfs: new insights

Córsico

Althaus

Bertolami

et al. 2019

Astron Astrophys Rev

205

224

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Stars are extremely important astronomical objects that constitute the pillars on which the Universe is built, and as such, their study has gained increasing interest over the years. White dwarf stars are not the exception. Indeed, these stars constitute the final evolutionary stage for more than 95 per cent of all stars. The Galactic population of white dwarfs conveys a wealth of information about several fundamental issues and are of vital importance to study the structure, evolution and chemical enrichment of our Galaxy and its components -including the star formation history of the Milky Way. Several important studies have emphasized the advantage of using white dwarfs as reliable clocks to date a variety of stellar populations in the solar neighborhood and in the nearest stellar clusters, including the thin and thick disks, the Galactic spheroid and the system of globular and open clusters. In addition, white dwarfs are tracers of the evolution of planetary systems along several phases of stellar evolution. Not less relevant than these applications, the study of matter at high densities has benefited from our detailed knowledge about evolutionary and observational properties of white dwarfs. In this sense, white dwarfs are used as laboratories for astro-particle physics, being their interest focused on physics beyond the standard model, that is, neutrino physics, axion physics and also radiation from "extra dimensions", and even crystallization.The last decade has witnessed a great progress in the study of white dwarfs. In particular, a wealth of information of these stars from different surveys has

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An unusual white dwarf star may be a surviving remnant of a subluminous Type Ia supernova

Cited by 88 publications

References 46 publications

Remnants of Subdwarf Helium Donor Stars Ejected from Close Binaries with Thermonuclear Supernovae

Remnants of Subdwarf Helium Donor Stars Ejected from Close Binaries with Thermonuclear Supernovae

Observational properties of thermonuclear supernovae

Pulsating white dwarfs: new insights

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