What type of star is Polaris classified as?

Polaris is classified as a Cepheid variable star, which is significant due to its unique properties and its role in the field of astronomy. Cepheid variables are a type of pulsating star known for their predictable variations in brightness, which occur over a regular period. This characteristic allows astronomers to use them as "standard candles" to measure cosmic distances.

Polaris's variability is tied to its intrinsic luminosity, which correlates closely with its pulsation period. Because of this relationship, astronomers can determine its distance from Earth. Furthermore, Polaris serves as an important navigational reference in the night sky due to its brightness and position very close to the North Celestial Pole.

In contrast, the other types of stars mentioned, such as luminous blue supergiants, red giants, and red supergiants, are distinct classifications with different physical characteristics and evolutionary stages that do not apply to Polaris. Luminous blue supergiants are hot and massive, red giants expand and cool after exhausting their nuclear fuel, and red supergiants represent later stages of stellar evolution with much larger radii compared to Polaris's characteristics. Hence, their classification does not align with the properties and behavior exhibited by Polaris as a Cepheid variable star.