In a previous episode, we crushed that idea
that the Universe is perfect for life.
It’s not.
Almost the entire Universe is a horrible and
hostile place, apart from a fraction of a
mostly harmless planet in a backwater corner
of the Milky Way.
While living here on Earth takes about 80
years to kill you, there are other places
in the Universe at the very other end of the
spectrum.
Places that would kill you in a fraction of
a fraction of a second.
And nothing is more lethal than supernovae
and remnants they leave behind: neutron stars.
We’ve done a few shows about neutron stars
and their different flavours, so there should
be some familiar terrain here.
As you know, neutron stars are formed when
stars more massive than our Sun explode as
supernovae.
When these stars die, they no longer have
the light pressure pushing outward to counteract
the massive gravity pulling inward.
This enormous inward force is so strong that
it overcomes the repulsive force that keeps
atoms from collapsing.
Protons and electrons are forced into the
same space, becoming neutrons.
The whole thing is just made of neutrons.
Did the star have hydrogen, helium, carbon
and iron before?
That’s too bad, because now it’s all neutrons.
You get pulsars when neutron stars first form.
When all that former star is compressed into
a teeny tiny package.
The conservation of angular motion spins the
star up to tremendous velocities, sometimes
hundreds of times a second.
But when neutron stars form, about one in
ten does something really really strange,
becoming one of the most mysterious and terrifying
objects in the Universe.
They become magnetars.
You’ve probably heard the name, but what
are they?
As I said, magnetars are neutron stars, formed
from supernovae.
But something unusual happens as they form,
spinning up their magnetic field to an intense
level.
In fact, astronomers aren’t exactly sure
what happens to make them so strong.
One idea is that if you get the spin, temperature
and magnetic field of a neutron star into
a perfect sweet spot, it sets off a dynamo
mechanism that amplifies the magnetic field
by a factor of a thousand.
But a more recent discovery gives a tantalizing
clue for how they form.
Astronomers discovered a rogue magnetar on
an escape trajectory out of the Milky Way.
We’ve seen stars like this, and they’re
ejected when one star in a binary system detonates
as a supernova.
In other words, this magnetar used to be part
of a binary pair.
And while they were partners, the two stars
orbited one another closer than the Earth
orbits the Sun.
This close, they could transfer material back
and forth.
The larger star began to die first, puffing
out and transferring material to the smaller
star.
This increased mass spun the smaller star
up to the point that it grew larger and spewed
material back at the first star.
The initially smaller star detonated as a
supernova first, ejecting the other star into
this escape trajectory, and then the second
went off, but instead of forming a regular
neutron star, all these binary interactions
turned it into a magnetar.
There you go, mystery maybe solved?
The strength of the magnetic field around
a magnetar completely boggles the imagination.
The magnetic field of the Earth’s core is
about 25 gauss, and here on the surface, we
experience less than half a gauss.
A regular bar magnet is about 100 gauss.
Just a regular neutron star has a magnetic
field of a trillion gauss.
Magnetars are 1,000 times more powerful than
that, with a magnetic field of a quadrillion
gauss.
What if you could get close to a magnetar?
Well, within about 1,000 kilometers of a magnetar,
the magnetic field is so strong it messes
with the electrons in your atoms.
You would literally be torn apart at an atomic
level.
Even the atoms themselves are deformed into
rod-like shapes, no longer usable by your
precious life’s chemistry.
But you wouldn’t notice because you’d
already be dead from the intense radiation
streaming from the magnetar, and all the lethal
particles orbiting the star and trapped in
its magnetic field.
One of the most fascinating aspects of magnetars
is how they can have starquakes.
You know, earthquakes, but on stars… starquakes.
When neutron stars form, they can have a delicious
murder crust on the outside, surrounding the
degenerate death matter inside.
This crust of neutrons can crack, like the
tectonic plates on Earth.
As this happens, the magnetar releases a blast
of radiation that we can see clear across
the Milky Way.
In fact, the most powerful starquake ever
recorded came from a magnetar called SGR 1806-20,
located about 50,000 light years away.
In a tenth of a second, one of these starquakes
released more energy than the Sun gives off
in 100,000 years.
And this wasn’t even a supernova, it was
merely a crack on the magnetar’s surface.
Magnetars are awesome, and provide the absolute
opposite end of the spectrum for a safe and
habitable Universe.
Fortunately, they’re really far away and
you won’t have to worry about them ever
getting close.
Another episode, another bizarre stellar object
studied.
What would you like us to talk about next?
Let us know in the comments.
In our next episode, we wonder how close moons
can orbit before they get torn apart.
Oh, and make sure you stick around for the
blooper.
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