pelkistymisvaiheessa

Pelkistymisvaiheessa refers to a stage in the life cycle of a star, specifically a red giant or supergiant, where the star is undergoing significant changes in its internal structure and energy production. This phase is characterized by the star's outer layers expanding and cooling, causing it to become much larger and brighter than it was in its previous stage. The core of the star, however, is contracting and heating up, leading to increased nuclear fusion rates.

During the pelkistymisvaiheessa, the star's outer layers can extend to hundreds or even thousands of times their original size, creating a red giant or supergiant. The increased surface area results in a lower surface temperature, giving the star a reddish hue. The star's luminosity also increases significantly, making it one of the brightest objects in its galaxy.

The pelkistymisvaiheessa is a relatively short stage in a star's life, lasting only a few million years compared to the billions of years the star spends in its main sequence stage. After this phase, the star will continue to evolve, eventually leading to its death as a white dwarf, neutron star, or black hole, depending on its initial mass.