What type of star is Betelgeuse?

Betelgeuse is classified as a red giant star, which is consistent with its characteristics. Red giants are stars that have expanded and cooled after exhausting the hydrogen fuel in their cores. They possess a large radius and a lower surface temperature compared to main-sequence stars, giving them a reddish hue.

Betelgeuse is located in the constellation Orion and is known for its distinctive red color and impressive size. It has expanded significantly beyond its original size as a main-sequence star, which highlights its evolution on the Hertzsprung-Russell diagram where stars transition from main-sequence to red giant phases.

Other classifications such as white dwarf and blue supergiant do not apply to Betelgeuse. White dwarfs represent the remnants of stars that have shed their outer layers and are left with a dense core, while blue supergiants are very massive stars that burn through their fuel rapidly and are much hotter and larger than Betelgeuse. Main-sequence stars, on the other hand, are in the prime phase of their life cycle where they fuse hydrogen into helium, a stage that Betelgeuse has already surpassed.