Biggest Explosions in the Universe Powered by Strongest Magnets
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What I'm wondering is, was the object a Magnetar, prior to the Supernova? In which case, the prospect of a Magnetar going nova is pretty novel in and of itself. Or, was the Magnetar created during the nova? In which case, the ultra-long GRB was the result of creating a magnetar.
Yes, it's a neutron star with an exceptionally strong magnetic field. Under the right conditions, a star collapsing into a neutron star can become a dynamo-like object. The magnetic field lines around a magnetar constantly twist and turn, and sometimes a large amount of energy builds up and ultimately gets released that way.
Magnetars are rare, mainly because they last only a very short time (a couple of thousands of years, we believe), after that they're pretty much ordinary neutron stars.
> What I'm wondering is, was the object a Magnetar, prior to the Supernova?
Stars do have pretty strong magnetic fields in general. This has nothing to do with magnetars, but consider that solar flares happen when plasma from the star gets trapped in magnetic loops that are then suddenly released.
According to Wikipedia (thx tvmalsv!), ~10% of supernovae produce a Magnetar. However, the article states that only 1 in 10,000 - 100,000 supernovae will produce an UL-GRB. https://en.wikipedia.org/wiki/Magnetar
I see two options: 1) This was a star going nova, producing a Magnetar with a particularly strong magnetic field or 2) This was a Magnetar whose magnetic field decayed to the point that it caused a massive explosion/release of energy from the object.
Curious that they didn't explain this better, or perhaps I'm missing something obvious here.
> So, what is it about this event that makes it unique (i.e. produce ultra-long GRB).
In the case of supernovae, I believe the current model for producing UL-GRBs is that it has to be a massive star collapsing into a black hole, possibly followed by a relatively prolonged period of intense feeding on the star's remnants.
By contrast, a Magnetar discharging some of its built-up electromagnetic energy in our direction, could potentially be the more likely cause of any given long-lasting GRB.
> 1) This was a star going nova, producing a Magnetar with a particularly strong magnetic field
The GRB caused by a collapsing star would not be different based on whether the end product is a Magnetar or a normal neutron star.
> 2) This was a Magnetar whose magnetic field decayed to the point that it caused a massive explosion/release of energy from the object.
It's not the decay of the magnetic field that causes this, rather it's a localized build-up caused by the stresses of huge electromagnetic structures pushing and twisting against each other, until suddenly the whole things snaps and unwinds violently (much like a clock that gets wound up very tightly until it breaks).
From what I gathered, a Magnetar is a type of neutron star, and a neutron star is formed from the gravitational collapse after a supernova. About 10% of supernovas become magnetars (src: wikipedia, so... ;)