Supernova explosions

Nov 2, 2020
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My knowledges in this field are growing up more and more. I watched a lot of videos about this but I always got the most important informations or a little more without understanding deeply the topic. Now, I finally ask you this: what about the bursting stars? I mean, all the stars burst when they finish their fuel, but is this hydrogen and helium or only one. And more, is a matter of materials the reason of their explosion or something else as their age, their colour, etc...
I nearly forgot, I only want to say one last thing, I know the destiny of our Sun, it is gonna be a red giant and then a nebula because of the amout of mass that it has (not a lot in comparison of the other stars), for this reason we have to account the more-massive-stars-than-Sun that during this process will get this explosion and then, after them, there is the "creation", if you will, of Neutron Stars, even if I don't want to take in account them.
 
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Dec 9, 2020
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I suggest two sources for understanding the various stars in our Universe. 1. "The Life and Death of Stars" and 2. "Introduction to Astronomy". Both are courses produced by Learning Tree under the heading of "The Great Courses". These courses may be available via your local library. They will require a time commitment because they are extensive.
 
Nov 2, 2020
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Know the mass and you will know its future.
This is a really good beginning, anyway I want to know more. I have a problem with the "death" of stars, I know somethings about their final process, they begin to burn a different material, and then I don't know anything else. The next passage that I know is the explosion, Supernova or Red Giant, and now I sure that is only a question of mass...
I suggest two sources for understanding the various stars in our Universe. 1. "The Life and Death of Stars" and 2. "Introduction to Astronomy". Both are courses produced by Learning Tree under the heading of "The Great Courses". These courses may be available via your local library. They will require a time commitment because they are extensive.
Many thanks, I'll try it!!!
 
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Jun 1, 2020
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This is a really good beginning, anyway I want to know more. I have a problem with the "death" of stars, I know somethings about their final process, they begin to burn a different material, and then I don't know anything else. The next passage that I know is the explosion, Supernova or Red Giant, and now I sure that is only a question of mass...
The following basics may assist your learning....

1) All stars form from about 75% hydrogen and 25% helium. This is the stuff that came from the Big Bang. The expansion rate ~ 13.8 billion years ago caused primal matter to only form those two atoms, plus a tiny amount of lithium and a few other elements.

So, all stars consist of about that same proportion of hydrogen and helium. [I am ignoring how stars produce the other elements.]

Stars spend most their life in what is known the Main Sequence and understanding what happens during this period serves better to understand the other periods. So what happens....

1) Stars come from clouds, really big ones. Thousands of stars can emerge from a cloud that has gone through its phase of collapsing into thousands, sometimes hundreds of thousands, of regions.

2) Each collapse will have its own amount of mass that forms the central body.

3) If the mass formed exceeds about 1% that of the Sun's mass, the core density and temperature that has steadily gotten hotter and hotter during formation, will smoothly, IIRC, transition to fusing hydrogen. [Deuterium and lithium will likely fuse earlier but this is a story for protostars and pre-mainsequence stars, not main sequence stars that are in an equilibrium state.]

4) A very low mass star will take fuse hydrogen slowly. They are small and very dim. They use up their hydrogen and they're done.

Red dwarfs....Guaranteed to be a low mass star, some can be less than ~ 1% the mass of the Sun. Being a lightweight, it will last for perhaps a trillion years. So none have expired naturally. [I guess that’s a pun. :)]

5) More collapsed mass means the core will be more dense and it will have a higher temperature. Fusion will be far more productive. They are bigger and brighter.

As these more massive protostars form, their centers get hotter and hotter, much more so than the little red dwarfs. Eventually, the core conditions, as always, collapse to the point they will allow a smooth transition to hydrogen fusion.

But stars, like our Sun, have enough mass that as the hydrogen fuses to helium, the core itself will contract. Eventually, this shrinkage will have higher and higher temperatures and other conditions that will reach a point that helium fusion takes place.

But, surrounding this helium burning core is what? Hydrogen, right? So circumstances cab be that the inner core is fusing helium while the outer core is fusing hydrogen. I think that's true, eventually, for Sun-mass stars. [I know its true for the more massive ones.]

6) The really massive stars also go through this same process, but their greater mass causes a much faster rate of fusion. This makes them bigger and brighter.

These massive stars will slip off the Main Sequence, far sooner than the less massive stars, as they have layers of fusion, the top layer being hydrogen. They will continue to shrink as they consume their fuel until the point where the next element to burn is iron. When you fuse iron it absorbs energy. So if the star is massive enough to reach this point, the core will collapse as it fuses more and more iron, absorbing more and more energy, cooling the core, which triggers a super fast collapse. This triggers a supernova (Type II).
 
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Nov 2, 2020
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Thank you!
This passage, or better, the whole life of the stars is difficult both to explain and to understand, but you managed to explain it very well with a not very high lexicon!
The following basics may assist your learning....
If this is the basics I'm good knowing it, even if watching the final part I must say that it is fairly rich.
These massive stars will slip off the Main Sequence, far sooner than the less massive stars, as they have layers of fusion, the top layer being hydrogen. They will continue to shrink as they consume their fuel until the point where the next element to burn is iron. When you fuse iron it absorbs energy. So if the star is massive enough to reach this point, the core will collapse as it fuses more and more iron, absorbing more and more energy, cooling the core, which triggers a super fast collapse. This triggers a supernova (Type II).
Maybe I have to be careful understand better this part but it will not be hard having this as point of referment, thank you so much again. Anyways, I'm sure that thanks to you and the sources pointed by Sum85geo I'll have a good knowledge about them. Thanks guys!
 
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Nov 2, 2020
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Regarding the multiple layers of fusion for massive stars, perhaps this image will help. The "iron" in the core suggests this is close to going supernova.
This was one of the most important stumblingblocks that I found during my path, and now I want to say "was" because I understood everything about the chemistry of the Sun and the other stars... So, when they reach iron, there is the explosion, right? Thanks again!!!
 
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So, when they reach iron, there is the explosion, right? Thanks again!!!
Yes, but iron doesn't explode, of course. It's not like dynamite. The temperatures and pressures are such that silicon fuses into iron and this absorbs energy rather than produces energy (e.g. gamma rays). The lack of energy production cools and shrinks the core so that the pressure grows and more and more silicon fuses, so it shrinks more and more. This shrinkage is actually a millisecond sort of collapse of a gigantic object (ie core). This creates havoc for the rest of the star, and a supernova (Type II) is born.

Does this shrinkage greatly increase the fusion rate of all those upper layers to produce such an incredible explosion? That was once my assumption, but this seems to not be the case. Some sort of acoustic wave seems to propagate the explosion, but this also is a test of my memory. I haven't read recent info on this, admittedly.

If that core is massive enough, it will become a black hole,. If not, it will stop contracting when it becomes a neutron star. The electrons and protons get crushed together into neutrons, but that is a gross simplification. Quantum effects are very active in this incredible energy state so that electrons and protons are hyper active, after all. Magnetic fields of incredible size can form and a Magnetar is born, though still a neutron star.

[Technically, a neutron star does not fit the definition to be a "star" since there is no fusion equilibrium as required. Perhaps someone will give this a better name. There's hope for this since it's now rare to see someone say "white dwarf star" but, rather, "white dwarf" is used. Being pedantic, they are likely the strongest blue object emitters in the universe, and it takes a very long time for them to cool down to white, and so forth.]
 
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Nov 2, 2020
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Nono, iron doesn't explode. Iron was put at stake by me only because of his behave in this field, he cannot be used in nuclear reactions...
Thanks to some videos and your photo of the Sun's core (of course, all the stars) I managed to understand a lot despite all the work I had to do during this days. I was absent here indeed. Anways, if I understood something, is that the stars with a low mass, the Sun for instance, belongs the type I and are forced to become firstly a huge red star, secondly a dwarf, even if I didn't know the existence of blue dwarfs...
I nearly forgot, Neutron Stars and Black Holes are metamorphosis of stars that belongs the type II stars! For this reason in my opinion they are rougly the same thing.
Magnetic fields of incredible size can form and a Magnetar is born, though still a neutron star.
I read something about them too, but them are only a subset of Neutron Stars, aren't they?
 
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Here are some interesting items you may wish to look at:

Neutron star - Wikipedia

The Magnificent Seven (neutron stars) - Wikipedia

Neutron Stars, Pulsars, and Magnetars - Introduction (nasa.gov)

What Is a Neutron Star? | Live Science

Regarding the name: "Most known neutron stars belong to a subclass known as pulsars."
I know this is not technically correct as an alternative name, but maybe it is a signpost?

If you might wish to buy a neutron star, this may be useful??????

Neutron Stars at Amazon - Neutron Stars, Low Prices

Enjoy!

Cat :)
 
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Nov 2, 2020
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Here are some interesting items you may wish to look at:
Thank you too. I must say that after many attempts I managed to reach my goal, the understanding of stars' evolution. I know the most important steps and other features even in greater details. Now this will be all an easy path with Neutron Stars, Black Holes ( that are rather well known by me) and White Dwarfs ( even if I'm not so interested by them). Thus, thank you expecially for the pulsating stars that are the last ( or at least I hope that) stumbling block in this field of cosmology.
If you might wish to buy a neutron star, this may be useful??????
I have already heard something of this kind...
There was a man that gained a lot claiming to be the owner of the whole solar sistem (outside Earth, of course). Many people across the world wanted to buy slices of the surfaces of the planets and the prices weren't even so high. I don't remember this perfectly and I don't know even if this is true, but I remeber this because of the oddity. Sometimes I'm surprised for the evolution of science, but now and then it seems to me that many people are outside this.
 
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