Astronomy

In 2-3 paragraphs, answer the following prompt thoroughly, clearly, and in detail:

We have learned that low-mass stars like the Sun actually go through two phases of expansion late in their lives, during which they become much larger and much redder at their surfaces. In 2-3 thorough, clear, and detailed paragraphs, explain the key differences in the processes happening in the central regions and their effects on the star’s outer atmosphere during these two phases in the life of a one Solar mass star. Why does the first red giant phase end so much differently than the second red giant phase does? (HINT: Be sure to address what’s going on in both expansions! With examples and details!)

Hydrogen fusion begins in the cores of stars when their temperatures reach about 10 million K. Helium fusion in stars requires much higher temperatures, closer to 100 million K. Why does helium require such high temperatures before it will fuse into heavier elements? (HINT: Explain why it needs to be so hot!)