Large, bright stars that are fairly cool are called red giants.

Here's why:

* Large: Red giants are much larger than our Sun, often with diameters hundreds of times greater.

* Bright: They emit a lot of light, making them very luminous.

* Cool: Despite being bright, their surface temperature is relatively low, around 3,500 to 5,000 Kelvin. This gives them a reddish color, hence the name "red giant."

Red giants are a stage in the evolution of stars like our Sun. As they run out of hydrogen fuel in their core, they expand and cool, becoming red giants.