

Biggest Explosions in the Universe Powered by Strongest Magnets - dnetesn
http://www.eso.org/public/news/eso1527/

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krohling
I'm still not clear on the process they're describing. According to the
article, a Supernova was "powered by the decaying super-strong magnetic fields
around an exotic object called a magnetar". This is what caused the ultra-long
GRB.

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.

~~~
Udo
_> Or, was the Magnetar created during the nova?_

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.

~~~
krohling
Right, magnetars are neutron stars, which are produced during supernovae. So,
what is it about this event that makes it unique (i.e. produce ultra-long
GRB).

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](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.

~~~
Udo
I think the misunderstanding might come from the fact that a Magnetar produces
many gamma ray bursts over thousands of years until it finally runs out of
energy, but a supernova is a completely different process which happens only
once per star.

 _> 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).

