What is the last stage in the evolution of the Sun before it turns into a planetary nebula?

1 Answer
Apr 13, 2016

After the Second Red Giant Stage.


A normal sized Star like our Sun burns through it's fuel slowly as compared to a high mass star. It has a lifetime of about 10 Billion years, right now our Sun is in it's main sequence stage where it is burning hydrogen into helium, so the core is now filling slowly up with Helium. After it has consumed all of it's hydrogen the core will collapse making the outer layers to expand.

The temperatures inside the core are high enough to initiate helium burning due to the intense pressure at the core. But the Sun will still be burning hydrogen also in a shell surrounding the core.

A time will come when Sun burns all of it's Helium into Carbon and when all of it's Helium is gone the core collapse due to the inward acting gravity as there is no pressure to balance the gravity, pressure that was generated due to Nuclear Fusion as a result the outer layers will expand so much that the Star is dispersed into Space in the form of a Planetary Nebula with a White Dwarf at it's center.