Spherical Symmetry/Simultaneity of Supernova Explosions

[Islam Hassan]

If the timing of detonation of nuclear weapons’ numerous implosive lenses must to be kept to within a microsecond or so in order to avoid asymmetrical detonation, does the timing of a supernova explosion similarly have tight constraints on its simultaneity and hence the sphericity of its ultimate cataclysmic implosion/explosion?

What are these constraints estimated to be, and are they occasionally breached? Have we observed asymmetric —or slightly asymmetric— supernova explosions?IH

 

[mathman]

https://en.wikipedia.org/wiki/Supernova

Above should help. The core is essentially spherical, so there is no reason to expect anything else. However our observations are from one direction, so asymmetry may be hard to detect.

 

[alantheastronomer]

There's going to be asymmetry due to differential rotation - varying angular momentum with angle from the equator. Look at the Crab nebula - it's somewhat misshapen and oblong.

 

[Vanadium 50]

As far as we know, supernovae are asymmetric. There is no models of symmetric supernovae that provide a) an explosion and b) a remnant. Since we see both, we know the symmetric models are wrong.

 

[alantheastronomer]

To explain further - We still don't have successful models of type II supernova explosion mechanisms, so we don't know how they explode. Don Lamb at the University of Chicago was able to produce a successful model of a carbon detonation supernove - one produced by an accreting white dwarf star - but only if the explosion originated off-center.

 

[Islam Hassan]

If the numerous implosive lenses on a nuclear weapon typically have to detonate within less than a microsecond, do we have an estimate of the ‘detonation’ interval window for supernovae?IH

 

[alantheastronomer]

If the numerous implosive lenses on a nuclear weapon typically have to detonate within less than a microsecond, do we have an estimate of the ‘detonation’ interval window for supernovae?IH

The explosion mechanism for a supernova is not the same as for a nuclear weapon. The core of the massive star that forms the supernova turns into a neutron star that doesn't detonate, so the timing of the infall of the outer layers of the star is less critical for production of the explosion. Indeed, we're not sure if the outer layers of the star infall at all before the explosion occurs.

 

[Islam Hassan]

Thanks for all your answers. Conceivably then, could a supernova explosion develop fully over a span of minutes or hours even? Would there theoretically be an upper limit on this time interval?IH

 

[alantheastronomer]

The collapse of the stellar core to becoming a neutron star occurs on a freefall timescale and takes only a matter of seconds! Observations of neutrinos coming from the core of Supernova 1987a came several hours before the light signal from the event was observed, so the explosion developed over the span of a few hours. Presumably the more massive the star, the longer the interval for the explosion to develop.