What is the second nd longest stage in the life of a star?

The second longest stage in the life of a star is the main sequence phase. During this stage, which can last billions of years, a star fuses hydrogen into helium in its core, generating energy that balances gravitational collapse. This phase represents a stable period where the star maintains its size and temperature, allowing it to shine steadily. After exhausting its hydrogen fuel, a star will transition to later stages such as the red giant phase.