The Black Sun?!

Yep. Life throws us curveballs sometimes. However, we should not expect a very small and dense ball made out of our Sun!

Why? Because the Sun is not heavy enough to be pressed into a black hole by its own gravity when its time comes.

First of all, let us simplify how does any star “work” and what it is made of after all?!

The question is not as simple as you may think. Let’s skip times when people believed that this luminary object in the sky was a chariot of the god Helios, on which he rode back and forth across the sky every day like a poor taxi driver in New York city. You will be surprised to know that ancient Greeks were not totally wrong about that god, but first things first. 

In some centuries people came to the conclusion that the stars were huge balls of… something. However, that time they didn’t figure out that it is possible to identify that “something” through analyzing the spectrum of the star light. And they produced a number of theories on the star material. I love coal theory for example. I know that it is not true, and yet it fascinates me! We really believed that the Sun was just a huge furnace. And not so long ago by the way!

This theory shows us the general direction of the scientists’ reflections at those times. They were looking for something that could burn. However, as scientific methods were developing it was understood undoubtedly that our star is made of… helium and hydrogen! So what makes ordinary elements act not like any good gases somewhere on earth, but glow, emitting monstrous amounts of radiation, heat and light?!

It is density. Density so high that not atoms themselves but their nuclei come close to each other. Not only do they come close, they are literally smeared on each other forming new elements.

The simplest “smearing” goes like this… Wait a little bit! Do you remember your chemistry lessons at school?! If not, let us recall them together! Atoms contain a number of “+” particles and “0” particles in their nuclei. If we take an element with number 8 in the periodic table, we’ll see that its nucleus is formed with 8 `+ protons and some `0 neutrons. It usually goes with a set of 8, 9 or 10 neutrons. 8, 9 or 10 decides what kind, sort or using chemical language isotope it is. By the way, this element with 8 protons and 8 or 9 or 10 neutrons in its nucleus is called oxygen and you’ve breathed some amount of it while reading this paragraph.

As we settled it, let’s go on. In normal life everything reacts with everything, but nuclei remain untouched. It means that if you put your old iron… sword to the fresh air it will react with oxygen and water forming rust. Rust’s formula (oh yeah, each substance has its own formula) is Fe2O3, which means that 2 atoms of iron are now bound with 3 atoms of oxygen forming a rust molecule. But. Iron remains still iron and oxygen remains still oxygen in this molecule.

That’s the difference between a chemical reaction and nuclear fusion that takes place in the core of a star! As you can guess from the name of the latter process the nuclei are fused in it, so we get new elements in the end.

Do you want a simple example? Here it goes!

A normal atom of hydrogen contains only 1 `+ proton in its nucleus.

In the core of the Sun 1 normal atom of hydrogen is smashed on the same 1 normal atom of hydrogen in such a way that 1 heavy atom of hydrogen is formed. Its core contains 1 `+ and 1 `0 particles. This sort (isotope)of hydrogen is called heavy hydrogen, or deuterium.

The next stage is going with joining 1 atom of deuterium with 1 normal atom of hydrogen. Nucleus is 2+1=3, which means 2 `+ and 1 `0 particles. As we have now two protons, we don’t see hydrogen anymore. Okay, we didn’t see it anyway, but believe me, it’s like that! We face a brand new element called helium (now remember ancient Greeks and their taxi god Helios please). Newborn atom of helium is still underweight, so it attracts another 1 atom of normal hydrogen and nuclearfuses with it, let us say so. And we get 1 normal atom of helium (2 `+ and 2 `0).

What is so special about all this nuclei merging? you will probably ask.

Special is that the process frees such an enormous amount of energy that the star can even resist the old good power of gravity. The gravity wants to squeeze it into a dot, but the energy released as a result of nuclear fusion acts in an opposite direction. And this status quo lasts for years. For billions of years.

However, everything comes to an end, even hydrogen fuel. And the day comes when all hydrogen has been converted into helium. What’s next? It actually depends on the mass of a star and we have three options here. One of them , we are particularly interested in today, are medium sized and medium rare stars so to say. Just like our Sun. 

As the gravity remains the same and the power of nuclear fusion reduces, our star begins to contract. That gives us additional heat, as a result hydrogen that was in outer layers starts its own nuclear fusion, like its hydrogen brother-in-core did before. However, this second portion of fuel comes to an end as well. And there is no force to resist the gravity now. So, outer layers of the Sun will be thrown away in last core convulsions forming a beautiful planetary nebula. I hope our nebula will be beautiful. And will inspire someone looking at it in the telescope from the opposite side of our galaxy. And all the remaining material will be pressed into a ball the size of Mars. This ball is called a white dwarf.

It will gradually dim and cool, and form a dark star remnant, a black dwarf. However, this process is so long, that I can’t show you any black dwarf. Somehow the scientists counted that it takes about 10 trillion years for the black dwarf to cool fully. And our baby-universe is just 13,7 billion years old. So, wait a little bit!

I hope I managed to convince you that if we are looking for an ancestor of a black hole, we should not do it in the Solar system. We should move on to the other areas of our galaxy. To the other distant stars.

Stay strong!

Dream big!

Enjoy our Sun while it has got some hydrogen!

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[…] you probably know the Sun will never become a black hole because it is not massive enough. And as a result it is not hot […]

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