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What is the next stage in a star's life after the main-sequence phase?

Answer 1

Red-Giant.

Following the main sequence stage, when a star burns hydrogen to helium, the star reorganizes itself, shrinking its core and expanding its outer layers to become a red giant.

At the Red-Giant stage, the star is dense enough to burn helium into carbon. This is necessary because fusing helium into carbon involves three fusion reactions, the first of which forms beryllium, which is extremely unstable. As a result, the star must be dense enough to support enough reactions to produce carbon.

Compared to its radius of 0.1 AU in the main sequence stage, the Sun's radius as a red giant is predicted to be approximately 2 AU.

149 Million km is one AU.

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Answer 2

Layla Anderson

A star moves into the red giant phase following the main-sequence phase.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.