Tuesday, March 18, 2014

New improved view of supernova explosion and death throes

Three-dimensional turbulent mixing in a stratified burning oxygen shell which is four pressure scale heights deep. 

The yellow ashes of sulphur are being dredged up from the underlying orange core. 

The multi-scale structure of the turbulence is prominent. 

Entrained material is not particularly well mixed, but has features which trace the large scale advective flows in the convection zone. 

Also visible are smaller scale features, which are generated as the larger features become unstable, breaking apart to become part of the turbulent cascade. 

The white lines indicate the boundary of the computational domain. 

Credit: Arnett, Meakin and Viallet/AIP Advances

A powerful, new three-dimensional model provides fresh insight into the turbulent death throes of supernovas, whose final explosions outshine entire galaxies and populate the universe with elements that make life on Earth possible.

W. David Arnett
The model is the first to represent the start of a supernova collapse in three dimensions, said its developer, W. David Arnett, Regents Professor of Astrophysics at the University of Arizona, who developed the model with Casey Meakin and Nathan Smith at Arizona and Maxime Viallet of the Max-Planck Institut fur Astrophysik.

Described in the journal AIP Advances, it shows how the turbulent mixing of elements inside stars causes them to expand, contract, and spit out matter before they finally detonate.

Arnett, a pioneer in building models of physical processes inside stars, traces his fascination with turbulence to 1987A, the first supernova of 1987.

Located in a nearby galaxy, it was bright enough to see with the naked eye.

The star puzzled astronomers, Arnett recalled, because the material ejected by its explosion appeared to mix with material previously ejected from the star.

Existing models could not explain that. "Instead of going gently into that dark night, it is fighting. It is sputtering and spitting off material. This can take a year or two. There are small precursor events, several peaks, and then the big explosion.

"Perhaps what we need is a more sophisticated notion of what an explosion is, to explain what we are seeing," Arnett concludes.

More information: The article, "Chaos and turbulent nucleosynthesis prior to a supernova explosion" by David Arnett, Casey Meakin and Maxime Viallet appears in the journal AIP Advances (DOI: 10.1063/1.4867384). 

The article will be published online on March 18, 2014. dx.doi.org/10.1063/1.4867384

No comments:

Post a Comment