Low Mass Stars

Low-mass stars, defined as those with masses up to about twice that of the Sun, undergo a series of evolutionary stages:

1. Main Sequence: During this prolonged phase, low-mass stars fuse hydrogen into helium in their cores, maintaining stability for billions of years.

2. Red Giant: Once core hydrogen is depleted, fusion ceases, leading to core contraction and heating. This causes the outer layers to expand and cool, transforming the star into a red giant. In this phase, helium fusion begins in the core, while hydrogen fusion occurs in a surrounding shell.

3. Planetary Nebula: As helium in the core is exhausted, the star becomes unstable, shedding its outer layers into space. This ejected material forms a planetary nebula, illuminated by the remaining stellar core.

4. White Dwarf: The residual core cools and contracts into a white dwarf—a dense, Earth-sized remnant composed mainly of carbon and oxygen. Without further fusion, it gradually cools over time.

Notably, stars with masses less than approximately 0.5 times that of the Sun, such as red dwarfs, do not reach the red giant phase. Instead, they continue hydrogen fusion until their fuel is depleted, eventually cooling and fading as white dwarfs.

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