Tähekeha

Tähekeha, also known as the stellar body or star body, refers to the physical structure of a star, encompassing its core, radiative zone, convective zone, and outer layers. Stars are massive, luminous spheres of plasma held together by their own gravity, primarily composed of hydrogen and helium. The term "tähekeha" is commonly used in Estonian astronomy and astrophysics to describe the internal composition and processes that define a star’s lifecycle.

At the center of a star lies the core, where nuclear fusion—specifically the conversion of hydrogen into helium through the proton-proton chain or CNO cycle—releases vast amounts of energy. This energy generation sustains the star’s stability against gravitational collapse. Surrounding the core is the radiative zone, where energy moves outward primarily through radiative diffusion. In larger stars, a convective zone may exist above the radiative layer, where hot plasma rises, cools, and sinks in a circular motion, facilitating energy transport.

The outer layers of a star include the photosphere, the visible surface from which light is emitted, and the chromosphere and corona, which extend into the star’s atmosphere. The behavior of a tähekeha is influenced by its mass, age, and composition, determining whether it remains stable on the main sequence, evolves into a red giant, or undergoes supernova collapse.

Understanding tähekeha dynamics is crucial for astrophysics, as it helps explain stellar evolution, energy production, and the formation of heavier elements through nucleosynthesis. Observations and modeling of stellar interiors rely on techniques like helioseismology and asteroseismology, which analyze oscillations to infer internal structures.