What initiates the transition from the Main Sequence phase for a Sun-like star?
Answer
Depletion of hydrogen fuel in the core, leading to core contraction and shell burning
When the hydrogen fuel located in the star's center is exhausted, fusion stops there. Gravity causes the inert helium core to contract and heat up, which in turn ignites the surrounding hydrogen shell, starting the next phase of fusion.
Frequently Asked Questions
What initiates the transition from the Main Sequence phase for a Sun-like star?What physical changes cause a star leaving the Main Sequence to become a red giant?What are the primary drivers behind the intense mass ejection observed during the post-red giant phase?Compared to the hydrogen-fusing lifetime, how long does the entire post-red giant transformation last?What describes the remnant core exposed after the outer envelope has been expelled?What causes the ejected shell of gas to become visible as a planetary nebula?What is a characteristic temperature of the exposed white dwarf remnant responsible for creating the nebula?Why is the term "planetary nebula" considered a historical misnomer?What factors contribute to the diverse structural shapes observed in planetary nebulae?What is the ultimate fate of the remnant core after the planetary nebula fades away?