Labels:text | screenshot | circle OCR: SUPERGIANTS A MAIN-SEQUENCE star of at least 10 solar masses evolves into a supergiant. Inside a supergiant's core, a nuclear furnace fuses a series of successively heavier elements at temperatures of billions of degrees. The surface temperatures of these stars range from about 3,500 to 50,000 ℃ (6,300 to 90,000 ºF), which produces a range of colors from cool red to hot blue. Even those with relatively cool surfaces are as luminous as many thousands of CELESTIAL ALCHEMIST suns, however, because their huge Most of the elements we know today, surface areas give off such as carbon, oxygen, nitrogen, iron, so much radiation. gold, silver, and platinum, were created by nuclear reactions inside massive stars. SELECTED FACT STARS FILE