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The article says this is a Type II-P supernova; the wikipedia link says that's a core-collapse supernova, and results in a neutron star. It says the collapse of
by denton-scratch 4y ago
The article says this is a Type II-P supernova; the wikipedia link says that's a core-collapse supernova, and results in a neutron star. It says the collapse of the core occurs in seconds. I suppose the production of heavy elements and radiation must continue for days or weeks.
If a big star's core collapses to a neutron star in seconds, and the outer parts of the star get blown away due to reaching escape velocity, how does this thing keep blazing for four years? Is it really not a core-collapse supernova?
The article also says:
> Since 1954, the star has exploded six times.
How does that work? The thing can't be a core-collapse supernova; there's only so many times your core can collapse to a neutron star (roughly once).
It sounds from the WP article that what is being seen isn't the supernova explosion (which can surely only occur once), but the impact of a shockwave on a previous shell of exploding stuff. Which makes me suppose it's some kind of type I supernova?
- vikingerik 4y agoThe most likely hypothesis seems to be that there is a lot of interstellar material around the star, such that the ejecta is colliding with that and keeping it hot to keep glowing. It was a core-collapse supernova initially; the energy released from that is being absorbed and more slowly re-emitted by the thick surrounding material. (Thick in astronomical terms is still something like two hydrogen atoms per cubic meter.)
- denton-scratch 4y agoYeah, that's roughly what I figured (IANAA). But it still seems hard to explain six flashes bright enough to appear like a supernova. I'd expect the flash of any kind of supernova to be brighter than the flash of a shockwave hitting a shell of gas. But I know nothing. And anyway, for the shockwave from a supernova explosion to hit the shell of expanding gas from a previous explosion, that still seems to imply two supernova explosions from the same star. The only way I know that can happen is in a binary system.
- lazide 4y agoPerhaps it’s a hybrid? Original core collapse, then accretion of in falling material after the shock from the last explosion dissipates, causing spontaneous fusion/degeneracy again and re-explosion?