1. Mass: A star's mass is the single most important factor determining its evolution, lifespan, luminosity, temperature, and even its eventual fate. More massive stars burn hotter and brighter, but have shorter lifespans, while less massive stars are cooler, dimmer, and live for much longer.
2. Chemical Composition: The initial chemical composition of a star, primarily its hydrogen and helium content, affects its internal pressure, nuclear fusion rates, and overall energy output. Stars born from clouds with a higher proportion of heavier elements can be more luminous and have a different evolutionary path.
These two factors are intricately linked and work together to shape a star's life story.
