The Beginning and Ends of Double White Dwarfs

Session

Supernovae & their Aftermath

4 Jul 2019, 09:30

Main Auditorium (Geological Museum)

Conveners

Supernovae & their Aftermath

• Na'ama Hallakoun

Supernovae & their Aftermath

• Stephen Justham (University of Amsterdam )

Supernovae & their Aftermath

• Anthony Piro (Carnegie Observatories)

32. The Fastest Stars in the Galaxy: Confirmation of the D6 Type Ia Supernova Scenario

Ken Shen (UC Berkeley)

04/07/2019, 09:30

Talk

The binary companion and mechanism responsible for triggering the explosion of a white dwarf (WD) as a Type Ia supernova (SN Ia) have been the subject of intense research for decades. In the “dynamically driven double-degenerate double-detonation” (D6) scenario, the binary companion is another WD that begins to undergo unstable mass transfer. The violence of this dynamical accretion leads to a...

2. Three-dimensional simulaitons of double detonations in the double-degenerate models for type Ia supernovae

Ataru Tanikawa (The University of Tokyo)

04/07/2019, 10:05

Talk

The discovery of hypervelocity white dwarfs strongly supports the Dynamical-Driven Double-Degenerate Double-Detonation ($D^6$) model for type Ia supernova scenario. We have performed high-resolution SPH simulations of $D^6$ explosions in various double-degenerate systems. We have found several explosion modes. In this presentation, we will show observational features of these explosion modes.

41. Type-Ia supernovae from mergers of hybrid He-CO WDs and CO WDs

Prof. Hagai Perets (Technion)

04/07/2019, 11:10

Talk

Type-Ia supernovae (SNe) are thought to originate from the thermonuclear explosions of carbon-oxygen (CO) white-dwarf (WD) stars. They produce most of the Iron-peak elements in the universe, and bright Ia-SNe serve as important “standard candle” cosmological distance-indicators. The proposed progenitors of standard type Ia-SNe had been studied for decades and can be generally divided between...

6. The Origin of Standard Thermonuclear Supernovae from Hybrid White Dwarf Mergers

Mr Yossef Zenati (Technion)

04/07/2019, 11:30

Talk

Type-Ia supernovae (SNe) are thought to originate from the thermonuclear explosions of carbon-oxygen (CO) white-dwarf (WD) stars. The proposed progenitors of standard type Ia-SNe can be generally divided between explosions of CO-WDs accreting material from stellar non-degenerate companions (single-degenerate; SD models), and those arising from the mergers of two CO-WDs (double-degenerate; DD...

29. Runaway White Dwarfs after Shocks from Supernova Ejecta

Evan Bauer (UC Santa Barbara)

04/07/2019, 11:50

Talk

In the D6 scenario for Type Ia supernovae, the lower mass white dwarf is in a close orbit while donating material to its companion that explodes as a supernova. This orbit leads to the high velocities of runaway stars thought to be candidate white dwarf donor remnants from D6 systems. It also implies that the donor star should experience significant interaction with the supernova ejecta, which...

31. Hydrodynamic Evolution of Supernovae Impacting White Dwarf Donors

Matthew Coleman (Institute for Advanced Study)

04/07/2019, 12:10

Talk

The D6 scenario suggests that the white dwarf donor interacts significantly with the supernova ejecta, as a way to explain the luminosity and size of candidate remnant objects. As this is clearly a dynamical interaction, we use the self-gravity and newly developed EOS capabilities of Athena++ to explicitly evolve the hydrodynamical phase of the ejecta-donor interaction, with particular...

15. Three-Dimensional Simulations of White Dwarf Mergers and Turbulently-Driven Detonation Initiation

Robert Fisher (University of Massachusetts Dartmouth)

04/07/2019, 14:00

Talk

While the stellar progenitors of Type Ia supernovae (SNe Ia) remain a subject of active investigation, recent multi-wavelength observations of SNe Ia have tightly constrained near-Chandrasekhar mass (near-Mch) single-degenerate (SD) SNe Ia. In particular, the most extensive set of non-detections of nebular H-alpha from SNe Ia of 110 events of all classes (Tucker et al, 2019) guide us to...

14. Do sub-Chandrasekhar mass white dwarf explosions occur in nature?

Abigail Polin (UC Berkeley)

04/07/2019, 14:20

Talk

Carbon-oxygen WDs accreting a helium shell have the potential to explode in the sub-Chandrasekhar mass regime through the double detonation scenario, when a helium shell ignition propagates a shock wave into the the core of the WD causing a central ignition. I will present the results of a recent numerical parameter survey of hydrodynamic and radiative transport models of sub-Chandrasekhar...

20. Collisions of two white dwarfs and the associated nucleosynthesis

Prof. Jordi Isern (ICE,CSIC/IEEC)

04/07/2019, 14:40

Talk

Traditionally it has been assumed that the collision of two white dwarfs was a low probability event confined to the surroundings of the Galactic centre or to the core of globular clusters. Depending on the nature of the two stars (mass and chemical composition) and on the parameters of the collision (relative velocity and impact parameter) the outcome of the encounter can go from a simple...

54. Poster Advertisments

04/07/2019, 15:00

Poster

11. The double-degenerate model for the progenitors of SNe Ia

Dongdong Liu

Talk

Type Ia supervovae (SNe Ia) have been successfully employed as standard cosmological distance indicators. It has been found that the Universe is expanding at an increasing rate through the observation of SNe Ia, which reveals the existence of dark energy. However, the progenitors of SNe Ia are still unclear, which may affect the accuracy of the mearsured distance. Recently, both observational...