NAOJ: Surface Helium Detonation Spells End for White Dwarf

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NAOJ: Surface Helium Detonation Spells End for White Dwarf

Post by bystander » Thu Oct 05, 2017 2:37 pm

Surface Helium Detonation Spells End for White Dwarf
NAOJ | CfCA | Kavli IMPU | Univ of Tokyo | 2017 Oct 04
[img3="Artist’s impression of the supernova explosion. The nuclear detonation of the surface helium layer triggered an inward shock wave, and now carbon nuclear fusion has begun at the center. (Credit: University of Tokyo)"] ... fig2_s.jpg[/img3][hr][/hr]
An international team of researchers has found evidence that the brightest stellar explosions in our universe could be triggered by helium nuclear detonation near the surface of a white dwarf star. Using Hyper Suprime-Cam mounted on the Subaru Telescope, the team detected a type Ia supernova within a day after the explosion, and explained its behavior through a model calculated using the supercomputer ATERUI.

Some stars end their lives with a huge explosion called a supernova. The most famous supernovae are the result of a massive star exploding, but a white dwarf, the remnant of an intermediate mass star like our Sun, can also explode. This can occur if the white dwarf is part of a binary star system. The white dwarf accretes material from the companion star, then at some point, it might explode as a type Ia supernova.

Because of the uniform and extremely high brightness (about 5 billion times brighter than the Sun) of type Ia supernovae, they are often used for distance measurements in astronomy. However, astronomers are still puzzled by how these explosions are ignited. Moreover, these explosions only occur about once every 100 years in any given galaxy, making them difficult to catch. ...

A hybrid type Ia supernova with an early flash triggered by helium-shell detonation - Ji-an Jiang et al
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