- #1
songoku
- 2,328
- 336
- TL;DR Summary
- Sun will change to red giant then to planetary nebula and finally to white dwarf.
I want to know this process a little deeper so I searched and found this site:
https://theconversation.com/the-sun-wont-die-for-5-billion-years-so-why-do-humans-have-only-1-billion-years-left-on-earth-37379
This is part of the text from the link:
I want to ask several things:
1.
From the second paragraph: "As soon as the sun begins to burn more hydrogen, it would be considered a “red giant”. "
But from first paragraph: "But when the star has nothing left in the core to burn, gravitational forces take over".
I don't understand that part. I know energy is produced in core of the sun by nuclear fusion (fusing hydrogen to form helium) until hydrogen is used up but why the sun will begin to burn more hydrogen?
And also, what does it mean by "hydrogen in a small shell around the dead core" in second paragraph? I thought the hydrogen has already been used up?2. From the third paragraph:
a) why the outer region of star expands outwards when the core collapses due to gravitational force?
b) why the burning hydrogen in the shell around the core significantly increases the brightness of the sun?
c) why the surface cools down?
3. How red giant can turn into planetary nebula?
Thanks
I want to ask several things:
1.
From the second paragraph: "As soon as the sun begins to burn more hydrogen, it would be considered a “red giant”. "
But from first paragraph: "But when the star has nothing left in the core to burn, gravitational forces take over".
I don't understand that part. I know energy is produced in core of the sun by nuclear fusion (fusing hydrogen to form helium) until hydrogen is used up but why the sun will begin to burn more hydrogen?
And also, what does it mean by "hydrogen in a small shell around the dead core" in second paragraph? I thought the hydrogen has already been used up?2. From the third paragraph:
a) why the outer region of star expands outwards when the core collapses due to gravitational force?
b) why the burning hydrogen in the shell around the core significantly increases the brightness of the sun?
c) why the surface cools down?
3. How red giant can turn into planetary nebula?
Thanks