Hello wonderful person, this is Anton
and this right here is a neutron star
and a white dwarf.
Now many of you have been asking
what would actually happen if these two collided in real life,
what kind of effects would occur,
and what would actually result in their collision.
Today we're going to find out
because we're going to do some science using Universe Sandbox².
Welcome to "What Da Math?".
And let's actually start
with basically slowing down these two bodies,
making them stop completely,
and collide with one another.
Just so you can actually see what happens
in this video game
if you collide them together.
So i'm going to accelerate time here,
and you'll see that the
white dwarf will start approaching the neutron star,
and at some point collide with it.
Now you may not actually know what neutron stars and white dwarves are,
and if you don't actually know what they are,
check out some of the videos i made previously
that explains everything about them.
But basically white dwarf
is a type of
remnant star
that is about size of
our own planet Earth.
But actually our Sun will become as well,
one day our Sun will actually turn into something like this.
Neutron star on the other hand is something
a lot, a lot, a lot smaller.
Something maybe the size of a city
in real life.
But also has a similar mass to the white dwarf.
So,
this has a lot more density than this.
This also has a lot more surface gravity than this.
The actual values that we're talking about here
are...
Basically this thing is about 600 times bigger than this,
and at the same time, the gravitational field
on the neutron star,
is about 400,000 times higher than on the white dwarf.
Neutron stars also have much higher temperatures, they spin much faster,
and they produce a lot more magnetic field,
which makes them very very interesting objects.
And in this case this particular star is also a pulsar,
which is why it's pulsating so fast.
But when these two collide,
you can imagine things will go...
wrong, for both of them.
They'll change dramatically.
Now in this game, when they collide, this is what happens.
We're about to see their collision
in real time.
And...
here we go.
They turn into a supernova and they disappear completely.
Now the reality is a little bit more complicated than that.
Let's actually talk about
some of the realistic
systems where there are actually
both neutron star and
a white dwarf orbiting around one another.
But before we talk about
how and what happens to them,
let's actually talk about what...
created the central system. And here i'm just going to use Aldebaran
and Antares,
for a kind of
very short simulation of
how these systems came to be.
So these two stars are relatively large. They're a little bit..
or actually quite more massive than our Sun.
A lot more big in size as well.
An the important thing here to know is that these two stars were of different mass.
So long time ago..
the larger star, because it had so much more mass and so much more energy,
burned out and became a neutron star. So
this star right here will actually go supernova
- and i'll make this happen by basically clicking explode button right here -
and it'll actually turn into...
a neutron star. So right now this Antares
is now an Antares neutron star.
And then we basically had these two stars orbiting around one another.
So very very very tiny neutron star right there that still quite had a lot of mass,
and the main sequence star,
that was a little bit larger than our Sun, but very likely
a lot more mass... err, a lot less massive than the Antares right here.
And with time Antares very likely either sucked off a lot of the mass from this star,
making it a lot smaller, and eventually
turn to white dwarf,
or just waited until this star also exploded,
just like that,
and became a white dwarf.
So here's our Aldebaran white dwarf and Antares neutron star.
So now they're going to be orbiting around one another
for many many many millions and billions of years.
Now we can actually remove these supernovas because they're technically going to disappear with time.
And we're also just going to rename these into "white dwarf" and "neutron star".
So then these stars basically started to orbit one another,
and kind of existed together for a very long time.
But because there is a lot of interaction between them,
because there is a lot of really interesting effects including relativistic effects involved,
and basically a lot of gravitational waves are produced
from these two very dense bodies orbiting around one another,
with time these two will actually approach each other,
closer and closer and closer. We can actually simulate this by
manually moving them closer and closer together.
Now...
They are still very dense, they're still very very massive,
and...
a lot of things will very likely go wrong, the closer they move. So
a lot more gravitational waves are produced, they move even closer together,
and at some point, things will start going a little bit difficult for the white dwarf.
Because it's actually less dense than the neutron star
two things can happen.
One is that maybe the neutron star will actually start acquiring the...
the accretion disc around it that i'm trying to create right here,
but i know it's going to fly away as soon as i start the simulation. So
i'm just going to pause the time for now, and just show you what it may have looked like.
So there we go. So it might create an accretion disc
by essentially siphoning off
the material from the white dwarf.
And if this happens,
first of all there going to be a lot of nova explosions, so every time this becomes
critical mass, things will explode and a nova will occur
- about which you can learn in one of the videos i posted previously -
Or this thing might even create planetary bodies around the neutron star.
And we think that
the few neutron stars that we found that actually have
planets orbiting around them
may have actually acquired these planets
in such a way. So
there might be actually a planet here later on
that is going to orbit
around us. So let's just place Earth right here,
just for fun,
because this might represent
what will happen to
all this accretion stuff
with time.
But that's just one theory.
Another theory suggests that
as these two orbit closer and closer together,
the neutron star might actually
becomes what's known as the
Thorne Żytkow object
also known as TZO object.
In other words, the neutron star will actually go inside of the white dwarf,
and stay inside of it. It'll combine with the core of the white dwarf
creating this kind of a hybrid star.
Basically a white dwarf
that has a neutron star inside. And this is actually what you've seen right here.
There's a neutron star
on the inside, and around it, it has this white dwarf material
that's basically orbiting around it.
Now at some point,
this neutron star will very likely swole
the white dwarf completely and
then will either go supernova again,
or create a black hole.
Now,
all of the model simulations of
this TZO object appearing suggest that with time
all of the white dwarf / neutron star collisions will result in a black hole.
So basically, after a while this
will turn into this:
A black hole, right there that you see
in the center - we're actually going to rename this as "black hole" now.
And simply because an interaction between a neutron star material and a white dwarf material,
will eventually lead to instability,
and will very likely collapse and create the black hole.
And so here the black hole is actually going to slow this white dwarf,
and, that's it, here we go.
So this black hole is now very very beautiful covered in really interesting
explosion spots that will probably disappear if i accelerate time.
And as you can see this black hole is also spinning. It's a spinning black hole that we managed to create.
This is actually one of the few times i've seen a spinning black hole in Universe Sandbox.
And so that's very likely
the most likely scenario
of a collision between a neutron star
and
a white dwarf. It's not really a supernova, but it's very likely
either some kind of a nova followed by black hole,
or
a TZO or
basically a hybrid star
where neutron star
with a white dwarf around it
that'll then result
in a black hole.
And with the least likely scenario being
a neutron star that has
orbiting planets
in it's system.
So the white dwarf might actually turn into
a planetary system.
Anyway, so let's accelerate this and let's actuallt try this
dual system again, because i want to recreate this
from scratch just to show what exactly happened here
because you may have actually missed it.
And as you can see my spinning black hole slowly cooling down
and his spots are slowly disappearing,
making it a true
black hole, that it's about to become.
Anyway, so let's start a new simulation. I'm gonna show you how i did all of this.
We're going to select one of the pulsars on the bottom here.
Place it in the middle. Then we're going to use a balanced motion,
and slow down time of course,
and place a white dwarf, like for example Sirius B
around it. So let's just place it somewhere right here,
pause the game.
And so now you have these two objects
orbiting around one another project, pretty cool.
But the thing is...
because this is a much more dense object, and because this is a slightly less dense object,
they are actually interacting with each other
in terms of tidal forces as well. So
they're actually within each others
Roche lobes, and you can actually check that value
by going right here. So they're actually...
Oh, this object is actually
outside of it's Roche lobe limit, meaning a lot of it's mass is going to be lost,
and acquired
by the pulsar. And you'll see that happening
in a few seconds,
as soon as i start orbiting them aroud each other
you can even see...
If you click on the white dwarf you'll that it's actually going to start losing size and mass
progressively.
So it will get less and less mass because
the white dwarf is less dense,
and the neutron star is going to suck away some of it's mass for itself.
And there we go, so that's
the first acquiring of the mass from the white dwarf,
and as we basically run the simulation longer and longer,
the neutron star will start growing,
and the white dwarf will start
slowly shrinking
until...
at some point
the neutron star gets so big
and so massive
that it's basically
going to collide or collapse with
the white dwarf. And this is actually a pretty cool simulation to run
because it does show you
both the effects of the roche lobes
and the interaction of two very dense
very very massive objects.
And don't forget, these are actually more massives than our Sun,
even though in comprison to our Sun
they're absolutely tiny. Look how small they are.
They're barely size of our planet Earth.
But they're going to be creating a lot of
super-energy in a second, as soon as they collide.
Because they're actually going to disappear
and create a beautiful supernova.
And this is actually yet another possibility, but
mathematically, it's very unlikely to happen.
And if you're actually interested in this topic
there's a few papers i'm going to post about this.
You can read them in more details even tough they're kind of actually complex.
Took me a while to digest it myself.
And so here we go, at 3,
2, 1, they're already touching, they're going to explode any second now, and boom!
There's your supernova.
And so that's really all I wanted to say in this video and show you as well.
Hope you enjoyed this and hope you learned something from it. And if you did, don't forget to subscribe.
Share this video with someone who enjoys watching educational video games and related videos.
And someone who just like to learn stuff using video games.
I'll see you guys in the next video and we're going to learn something else about space, science or math.
And
space out.
See you later.
Don't forget to come back tomorrow to watch something else and learn something completely different.
And as always
See you later.
Bye bye.