<p>It's a question of pressure. When the hydrogen fuel in the centre of a star runs out, the helium "ash" starts to collapse under its own gravity, since there is no longer a source of energy within it to "hold it up". For a small star, that's that. You end up with a small ball of highly compressed helium sitting their slowly cooling down.  For slightly bigger stars the process is a bit "messier" involving the helium fusing further to carbon and oxygen and other processes that may "blow off" the outer layers of the star. Nevertheless the outcome is basically the same, except that now its a ball of carbon and oxygen slowly cooling.</p>

<p>It turns out though, that there is a limit to how much pressure any matter made up of nuclei and electrons in the usual way can support, and for stars more than a few times bigger than the Sun, that limit is reached. So, as fusion goes on, and the core of the star becomes larger and more and more compressed, it eventually collapses under its own gravity, driving the electrons into the nuclei where the combine with protons to form neutrons and becoming a neutron star. This happens rather suddenly and the resulting shock has a rather dramatic effect on the rest of the star, which is what we call a type II supernova. </p>

<p>The ball of neutrons is a neutron star, and may become a pulsar or a magnetar for a while before it calms down.</p>

<p>Even then, there is a limit to how much pressure a ball of neutrons can sustain, and if the star was very big the core may collapse further. If that happens it will become so dense that it will form a black hole and no further information will be able to escape it. </p>

<p>Of course all of this is, in some sense theory. We can see some evidence of all of these types of object, and we can see supernovae happening far away, but it's a bit hard to do experiments on this scale, and the objects and events are a bit rare to quickly build up a certain picture by observing. </p>

<p>It's also worth saying that there are some black holes that may never have formed from stars -- the really big ones at the centre of galaxies. They may just be the result of local density fluctuations in the early universe, which have subsequently grown. </p>

CC BY-SA 3.0
2018-03-30T12:03:56.973Z
2018-03-30T12:03:56.973Z
Steve Linton
<p>Why is it the some massive stars go supernovae and than either form a black hole, pulsar or a magnetar. All stars essentially go through the same process when they’re alive and burning through their fuel. It almost looks as if stars create everything in the universe one way or another, is it too far-fetched to think that black holes (theortical), pulsars and magnetars to name a few, could be completely different objects? Like have we actually witnessed the creation of any of these objects??</p>

CC BY-SA 3.0
2018-03-30T12:56:58.087Z
Its unclear what your question is: You start with "why do massive stars supernova"  There are then a couple of (incorrect) assertions (all stars are the same when alive). Then a different question "are black holes, pulsars different objects". Then a third question "Have we witnessed the creation of any of these".    None of which matches the title "creation after supernova"  Please [edit] to ask a single clear question.
James K
CC BY-SA 3.0
2018-03-31T21:23:35.060Z
I'm not sure what you mean by completely different objects.   Black holes, pulsars and magnetars are all stellar remnants though perhaps some black holes are primordial and not stellar remnants, but a star in main sequence is different than a stellar remnant post supernova.   Beyond that, I can't tell what you're asking.
userLTK
CC BY-SA 3.0
2018-04-01T05:03:59.587Z
james can you read? i don’t know where you got your details from my question. all stars are not the same when alive... hence why we have different types of stars man. My question was why do some massive stars form different objdcts...
arnelmujkic21
CC BY-SA 3.0
2018-04-01T05:06:23.993Z
You guys literally do not understand what I am asking... Steve was the only one to answer the question i was asking. Thank you steve
arnelmujkic21
CC BY-SA 3.0
2018-04-02T17:57:01.380Z
@arnelmujkic21 please do not be rude. James correctly pointed out that you do not have a confidential, clear question. The proper response to such a criticism is to clarify your question, not to become angry and accuse others of illiteracy.
Asher
<supernova>
creations after supernovas
arnelmujkic21
# creations after supernovas

(Asked by: username_0 on 2018-03-30)

Why is it the some massive stars go supernovae and than either form a black hole, pulsar or a magnetar. All stars essentially go through the same process when they’re alive and burning through their fuel. It almost looks as if stars create everything in the universe one way or another, is it too far-fetched to think that black holes (theortical), pulsars and magnetars to name a few, could be completely different objects? Like have we actually witnessed the creation of any of these objects??

**Tags:** supernova

> **Comments:**
> **username_1**: Its unclear what your question is: You start with "why do massive stars supernova"  There are then a couple of (incorrect) assertions (all stars are the same when alive). Then a different question "are black holes, pulsars different objects". Then a third question "Have we witnessed the creation of any of these".    None of which matches the title "creation after supernova"  Please [edit] to ask a single clear question.  
> **username_2**: I'm not sure what you mean by completely different objects.   Black holes, pulsars and magnetars are all stellar remnants though perhaps some black holes are primordial and not stellar remnants, but a star in main sequence is different than a stellar remnant post supernova.   Beyond that, I can't tell what you're asking.  
> **username_0**: username_1 can you read? i don’t know where you got your details from my question. all stars are not the same when alive... hence why we have different types of stars man. My question was why do some massive stars form different objdcts...  
> **username_0**: You guys literally do not understand what I am asking... username_4 was the only one to answer the question i was asking. Thank you username_4  
> **username_3**: @username_0 please do not be rude. username_1 correctly pointed out that you do not have a confidential, clear question. The proper response to such a criticism is to clarify your question, not to become angry and accuse others of illiteracy.  

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## 1 answers

### Answer by username_4 on 2018-03-30. Score: 2

It's a question of pressure. When the hydrogen fuel in the centre of a star runs out, the helium "ash" starts to collapse under its own gravity, since there is no longer a source of energy within it to "hold it up". For a small star, that's that. You end up with a small ball of highly compressed helium sitting their slowly cooling down. For slightly bigger stars the process is a bit "messier" involving the helium fusing further to carbon and oxygen and other processes that may "blow off" the outer layers of the star. Nevertheless the outcome is basically the same, except that now its a ball of carbon and oxygen slowly cooling.

It turns out though, that there is a limit to how much pressure any matter made up of nuclei and electrons in the usual way can support, and for stars more than a few times bigger than the Sun, that limit is reached. So, as fusion goes on, and the core of the star becomes larger and more and more compressed, it eventually collapses under its own gravity, driving the electrons into the nuclei where the combine with protons to form neutrons and becoming a neutron star. This happens rather suddenly and the resulting shock has a rather dramatic effect on the rest of the star, which is what we call a type II supernova.

The ball of neutrons is a neutron star, and may become a pulsar or a magnetar for a while before it calms down.

Even then, there is a limit to how much pressure a ball of neutrons can sustain, and if the star was very big the core may collapse further. If that happens it will become so dense that it will form a black hole and no further information will be able to escape it.

Of course all of this is, in some sense theory. We can see some evidence of all of these types of object, and we can see supernovae happening far away, but it's a bit hard to do experiments on this scale, and the objects and events are a bit rare to quickly build up a certain picture by observing.

It's also worth saying that there are some black holes that may never have formed from stars -- the really big ones at the centre of galaxies. They may just be the result of local density fluctuations in the early universe, which have subsequently grown.


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