krympningen

Krympningen, also known as the "shrinking" or "contraction" phase, is a significant event in the life of a star, particularly those with masses similar to or greater than that of our Sun. This phase occurs towards the end of a star's life, after it has exhausted the hydrogen fuel in its core and transitioned through the red giant phase. During krympningen, the star's outer layers are expelled into space, forming a planetary nebula, while the core of the star collapses under gravity, eventually becoming a white dwarf.

The term "krympningen" is derived from the Swedish word for "shrinking," reflecting the process by which the star's core contracts. This contraction is driven by the force of gravity, which pulls the star's mass inward, compressing the core to a much smaller size. The resulting white dwarf is incredibly dense, with a mass comparable to that of the Sun but a radius similar to that of Earth.

The planetary nebula that forms during krympningen is a beautiful and intricate structure, often resembling a butterfly or a ring. It is composed of the expelled outer layers of the star, which are enriched with heavy elements produced during the star's lifetime. These elements are then recycled into the interstellar medium, contributing to the formation of new stars and planetary systems.

Krympningen is a relatively brief phase in the life of a star, lasting only a few thousand years. However, the planetary nebula it produces can remain visible for tens of thousands of years, providing astronomers with valuable insights into the late stages of stellar evolution.