How are balls related to supernovas?

Hi,
well this question seems to be pretty strange. But balls are related in a bit complicated way to supernovas as you will see.
I was just watching cool video. I thought that it is cool enough that I will make a post about it, so here you go: stacked ball drop (thanks Physics Girl).


So in the video Physics Girl explains why when you stack balls on top of each other with increasing mass and let them fall that the top one will bounce so much.

When you have only one ball and you let it fall from some height, it will bounce less because there is energy which is used by the sound it makes, heat, friction and so on. When there is ball on the first one they drop at the same rate so they stay stacked on each other and then at one point where the lower one hits ground it is going to press little bit, conserving the energy and then bouncing back with the top ball still lying there on the surface of the lower one.

Top is going to be pushed harder by the lower one which causes it to bounce many more times than before since the first ball is heavier and stores more energy in the bounce.

Some videos will show you basketball ball, tennis ball and golf ball for example.

How is this related to supernova? Well what happens when massive star goes supernova is that in one of few types star’s core collapses, into neutron star or black hole.

Above, in A you have the onion like structure of huge star with various elements. In B the center collapses but there is so much energy it wont stay like this but it rather bounces from itself with tremendous speed ans as the other layers wanted to follow they will bounce even more like those balls about which I talked above. This is why there is so much energy in this explosion, each layer gets more energy than previous with the top one going of with tremendous energy in speeds close to speed of light.

The center is not able to escape but it rather collapses under its own gravity into black hole if it is heavy enough and if not than into neutron star.

Dragallur

1st picture
2nd picture

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Observing Supernova

Hi,
so what I just found was very very interesting and it is about observing of Supernovas which are those exploding stars or white dwarfs.


The problem with observation of these very bright objects is that first of all there is not much of them and second, it is extremely hard to catch the start of the explosion so we do not have much data about it.

This problem seems to have really awesome solution that is based on nothing else than Einstein’s gravitational lensing.

Gravitational lensing is effect of very massive thing like black hole or galaxy or even galaxy cluster. It can increase the amount of light coming to us or bend the light. So actually when you are looking to star right next to Sun it may appear on different spot than it actually is!

Actually I am pretty sorry but not only that you see everything in past but you see it actually on the wrong place, DAMN! (And if you run it is bluer).

So because of this light bending it can happen that the light even comes from different directions.

The picture above shows how we could observe one event (one supernova type Ia) four times in different time intervals just because it was in huge super cluster which bend the light from supernova so much that it came to us in different directions.

This particular observation was done only by accident when one astronomer was looking at pictures from Hubble and he saw it.

Dragallur

Supernova picture
Gravitational bending

PS: today I have reached 400 visitors!

 

Standard candle

Hi,
have you ever wondered how do scientists measure distances far away in space? Maybe you have heard about supernova which was found about 11 billions of light years away. The problem is that when something is far away you don`t actually know if what you see is bright or close or dim or far away or the combination of both.


So here comes the standard candle. The standard candle is object in Universe which has always about the same luminosity.
The example of thing that is not standard candle is for example any star since when you are looking at it you don`t know its luminosity since it could be in spectral class O or K  and it could be next to you or far away.

Standard candles are supernovas of type Ia which are the brightest of all supernovas.
First of all I will try to explain what this supernova type Ia is.

This type of supernova is explosion of white dwarf which exceeds the mass of 1.4 the mass of Sun.

How this happens? This white dwarf has to be in binary star system so he can feed on his companion`s gases and get the mass again to trigger fusion. When white dwarf exceeds the Chandrasekhar limit which is 1.4 of Sun`s mass as mentioned above then it explodes in violent explosion called supernova Ia.
Actually it is not so simple because the supernova explodes in what is called “double detonation” which is caused by first explosion happening even before Chandrasekhar limit because of the hydrogen which is fused on the surface on helium (I am going to find out more about this on astronomy stack exchange so I will update it.)

Then the second and main explosion is triggered and the donor, the first star is thrown away from the system by the energy released (1-2*10^44 J).

So the important thing is that supernova works as standard candle because it will be always about the same brightness which is very important because than astronomers can calculate how far away it is because they know how bright this thing is.
Supenovas are used for distances greater than 1,000,000 light years because closer there is not enough of them.

Dragallur

Picture source