tähtirakenne

Tähtirakenne refers to the internal structure of a star, describing how physical quantities like temperature, pressure, density, and chemical composition vary from the star's core to its surface. This structure is primarily determined by the star's mass and its evolutionary stage.

At the heart of a star lies the core, where nuclear fusion takes place, generating energy. Surrounding the core are various zones, such as the radiative zone and the convective zone, through which energy is transported outwards. The outermost layer is the stellar atmosphere, which includes the photosphere (the visible surface), the chromosphere, and the corona.

The balance between the inward pull of gravity and the outward pressure generated by nuclear fusion and thermal energy is crucial for maintaining a star's stability. This hydrostatic equilibrium dictates the overall structure. As a star evolves, its internal processes change, leading to transformations in its structure and outward appearance. For instance, as a star exhausts its core hydrogen, it may expand into a red giant, altering its internal energy transport mechanisms and surface temperature. Understanding tähtirakenne is fundamental to comprehending stellar evolution, nucleosynthesis, and the life cycles of stars.