<p>I won't primarily explain the H-R diagrams, because I think focussing on some of the underlying physics is essential for understanding, especially <a href="http://en.wikipedia.org/wiki/Stellar_nucleosynthesis" rel="nofollow">stellar nucleosytheses</a>.
For simplification let's assume the star initially consists of nothing else than ordinary hydrogen and traces of carbon and nitrogen.</p>

<p><a href="http://en.wikipedia.org/wiki/CNO_cycle" rel="nofollow">Nuclear fusion of hydrogen forms helium</a>; <a href="http://en.wikipedia.org/wiki/Triple-alpha_process" rel="nofollow">fusion of helium forms carbon</a>; <a href="http://en.wikipedia.org/wiki/Carbon_burning_process" rel="nofollow">fusion of carbon</a> leads to heavier elements like neon, also oxygen, sodium, magnesium; <a href="http://en.wikipedia.org/wiki/Neon-burning_process" rel="nofollow">neon decays to oxygen</a>; <a href="http://en.wikipedia.org/wiki/Oxygen-burning_process" rel="nofollow">oxygen fuses to silicon and others</a>; <a href="http://en.wikipedia.org/wiki/Silicon_burning_process" rel="nofollow">silicon fuses stepwise with helium to iron</a>. Each of these phases of burning needs higher temperature, and it releases energy. The phases can be subdivided in first core burning, then shell burning.</p>

<p>Earlier phases last long enough to be be visible from outside, resulting in motion within the HR diagram. Heating from phase to phase generally results in an overall expansion of the star.
The last phases last only a short time, too short to propagate effects to outside.</p>

<p>Fusion of iron consumes energy. Therefore the star gets a problem after the core consists of iron. Outer pressure cannot be stopped by fusion and further heating: The core collapses to a neutron star or a black hole, while the outer part is blown off by a <a href="http://en.wikipedia.org/wiki/Type_II_supernova" rel="nofollow">supernova</a>.
Neutron stars usually rotate rapidly, and cool down over very long periods of time.</p>

<p>After this overall framework you may go deeper into details of the phases.</p>

CC BY-SA 3.0
2016-12-29T17:05:56.333Z
Also crucial to describe the difference between core burning and shell burning and how that affects the HR diagram position.
ProfRob
CC BY-SA 3.0
2015-05-04T08:08:04.077Z
The underlying physics must include mass loss and rotation when considering such massive stars. And possibly binarity too.
ProfRob
CC BY-SA 3.0
2014-01-07T02:22:30.963Z
2014-01-07T02:22:30.963Z
Gerald
<p>Could you explain to me the life course for a massive star (30-40 solar masses) from birth to death using the HR Diagram (by showing key events in its life)?</p>

CC BY-SA 4.0
2021-04-29T11:37:19.980Z
Sounds like an exam question.
ProfRob
CC BY-SA 3.0
2013-12-28T18:19:13.077Z
This is quite broad, so it will be challenging to answer. I'll point to a few relevant links for reuse by answerers: [Wiki on Stellar evolution](https://en.wikipedia.org/wiki/Stellar_evolution), [Evolution of Massive stars](http://nu.phys.laurentian.ca/~fleurot/evolution/), [The Evolution of Massive Stars and Type II Supernovae](https://www.e-education.psu.edu/astro801/content/l6_p5.html), [Evolution of A Massive Star](http://zebu.uoregon.edu/~imamura/122/lecture-8/UMS.html), [Stellar Evolution II - Massive Stars](http://casswww.ucsd.edu/archive/public/tutorial/StevII.html).
TildalWave
CC BY-SA 3.0
2013-12-30T14:31:15.957Z
thanks. this link is the only link that is good http://zebu.uoregon.edu/~imamura/122/lecture-8/UMS.html  but in the middle it starts to confuse me regarding the HR diagram. do you have similar links? (& if someone  could post an answer here that would be great)  thanks.
JekylHyde
<star><formation><hr-diagram>
The life course for a massive star from birth to death using the HR Diagram
JekylHyde
# The life course for a massive star from birth to death using the HR Diagram

(Asked by: username_0 on 2013-12-28)

Could you explain to me the life course for a massive star (30-40 solar masses) from birth to death using the HR Diagram (by showing key events in its life)?

**Tags:** star, formation, hr-diagram

> **Comments:**
> **username_2**: This is quite broad, so it will be challenging to answer. I'll point to a few relevant links for reuse by answerers: [Wiki on Stellar evolution](https://en.wikipedia.org/wiki/Stellar_evolution), [Evolution of Massive stars](http://nu.phys.laurentian.ca/~fleurot/evolution/), [The Evolution of Massive Stars and Type II Supernovae](https://www.e-education.psu.edu/astro801/content/l6_p5.html), [Evolution of A Massive Star](http://zebu.uoregon.edu/~imamura/122/lecture-8/UMS.html), [Stellar Evolution II - Massive Stars](http://casswww.ucsd.edu/archive/public/tutorial/StevII.html).  
> **username_0**: thanks. this link is the only link that is good http://zebu.uoregon.edu/~imamura/122/lecture-8/UMS.html  but in the middle it starts to confuse me regarding the HR diagram. do you have similar links? (& if someone  could post an answer here that would be great)  thanks.  
> **username_1**: Sounds like an exam question.  

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## 1 answers

### Answer by username_3 on 2014-01-07. Score: 2

I won't primarily explain the H-R diagrams, because I think focussing on some of the underlying physics is essential for understanding, especially [stellar nucleosytheses](http://en.wikipedia.org/wiki/Stellar_nucleosynthesis).
For simplification let's assume the star initially consists of nothing else than ordinary hydrogen and traces of carbon and nitrogen.

[Nuclear fusion of hydrogen forms helium](http://en.wikipedia.org/wiki/CNO_cycle); [fusion of helium forms carbon](http://en.wikipedia.org/wiki/Triple-alpha_process); [fusion of carbon](http://en.wikipedia.org/wiki/Carbon_burning_process) leads to heavier elements like neon, also oxygen, sodium, magnesium; [neon decays to oxygen](http://en.wikipedia.org/wiki/Neon-burning_process); [oxygen fuses to silicon and others](http://en.wikipedia.org/wiki/Oxygen-burning_process); [silicon fuses stepwise with helium to iron](http://en.wikipedia.org/wiki/Silicon_burning_process). Each of these phases of burning needs higher temperature, and it releases energy. The phases can be subdivided in first core burning, then shell burning.

Earlier phases last long enough to be be visible from outside, resulting in motion within the HR diagram. Heating from phase to phase generally results in an overall expansion of the star.
The last phases last only a short time, too short to propagate effects to outside.

Fusion of iron consumes energy. Therefore the star gets a problem after the core consists of iron. Outer pressure cannot be stopped by fusion and further heating: The core collapses to a neutron star or a black hole, while the outer part is blown off by a [supernova](http://en.wikipedia.org/wiki/Type_II_supernova).
Neutron stars usually rotate rapidly, and cool down over very long periods of time.

After this overall framework you may go deeper into details of the phases.

> **Comments:**
> **username_1**: The underlying physics must include mass loss and rotation when considering such massive stars. And possibly binarity too.  
> **username_1**: Also crucial to describe the difference between core burning and shell burning and how that affects the HR diagram position.  

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