A very large star, in fact the most massive of the bunch. They are about 10 to 70 times the size of our Sun and can be hundreds of thousands of times brighter. Because of their extreme mass, they are very short lived compared to other stars with a life span of only 10 million years.
Because they live fast, die young and leave a beautiful nebula in their wake, supergiants can only been seen in places like the arms of spiral galaxies, open clusters and irregular galaxies. Places where new stars are born frequently.
Rigel, the brighest star in the constellation Orion is a typical blue-white supergiant, whereas Betelgeuse and Antares are red supergiants.
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