Red+Supergiants+2B

> Extremely massive supergiants can generate high enough pressure and temperature to fuse elements even heavier than carbon and oxygen. Near the end of the red supergiant phase, a high mass star will develop several layers of heavier and heavier elements. After a while stars this big explode and become a type 2 supernova
 * A red supergiant froms when a helium-burning red giants runs out of the helium in its core. After this happens, the core starts to collapse and heats up. This causes the outer layers of the star to expand and cool. As the star gets larger it will eventually become a red supergiant.
 * Red Supergiants are the largest stars in the universe in terms of physical size, but they are not the most massive.
 * The four largest known red supergiants in the Galaxy are Mu Chephei, KW Sagitarii V354 Cephei and KY Cygni, which all have a radius about 1500x larger than the sun.
 * The most massive of the red supergiants are thought to evolve to Wolf-Rayet stars, while lower mass red supergiants will likely end their lives as a type II supernova.
 * Red Supergiants can be 100x larger than our sun.
 * The luminosity of Betelgeuse is about 10,000x brighter than the sun.
 * The radius of Betelgeuse is about 370x larger than the sun.
 * 200 red supergiants have been discovered across the entire Milky Way Galaxy.
 * The red supergiant phase usually last about 500,000 years.
 * After a helium burning red giant runs out of helium fuel in its core, the star's core starts to collapse and heat up. This causes the outer layers of the star to expand and cool, similar to the process that occurred after the star ran out of hydrogen fuel and left the main sequence. As the star swells larger and larger, it eventually becomes a //red supergiant//.