Supernova simulations have shown how stellar explosions form debris clouds. Astronomers can now better interpret supernova remnant observations thanks to computer simulations of these catastrophic events by RIKEN astrophysicists.
When certain types of stars die, they are extinguished in an incredibly powerful explosion known as a supernova. One of the most common forms of supernova, type Ia, begins with a dense white dwarf that burns up all of its hydrogen. Matter emanating from the companion star sets off a nuclear fusion reaction in the dwarf, causing a massive fire that creates many of the heavier elements in the universe. They are thrown out in a luminous cloud, which bears the imprint of the explosion.
Astrophysicists have developed three-dimensional computer simulations that recreate supernovae. It consists of two stages: the first simulates the supernova explosion itself, and the second uses it as input for the supernova remnant model.
The team’s latest simulations have focused on two aspects of supernovae: how an explosion ignites inside a white dwarf, and how combustion rips apart a star. Ignition can start in just a few places inside the white dwarf, or it can start at many points at the same time. Meanwhile, combustion can be deflagration – a turbulent fire that travels slower than the local speed of sound – or it can involve deflagration followed by supersonic detonation.
Putting these options together in different ways, the researchers created four models of a supernova remnant. Each model has its own distinctive features. For example, a supernova with multiple ignition points and a deflagration explosion formed a remnant with an asymmetrical shell offset from the center of the explosion. In contrast, simulations using multiple ignition and detonation points resulted in a residue in which half of the outer shell was twice as thick as the other half. The remnants of the deflagration simulation also showed unexpected “seams” of a denser material.
These results indicate that the best time to see a supernova imprint on its remnant is about 100-300 years after the explosion. This imprint has been visible longer in supernovae with fewer flashpoints, and all remnants in the simulations as a whole have become spherical within 500 years. These results will help astronomers interpret observations of supernova remnants.