Stars like the sun When the core runs out of hydrogen fuel, it will contract under the weight of gravity. However, some hydrogen fusion will occur in the upper layers. As the core contracts, it heats up. This heats the upper layers, causing them to expand.
Stars more massive than the sun When the core runs out of hydrogen, these star fuse helium into carbon just like the sun. when the helium is gone, their mass is enough to fuse carbon into heavier element such as oxygen, silicon, neon, magnesium, sulfur and iron.
References http://www.silverstar- academy.com/Archive/Theory/Science/Atlantean_Protostar/Atlantean_Protos tar.htm http://physicsworld.com/cws/article/news/2006/feb/21/astronomers-find-a-mixed-up-solar- system http://spaceplace.nasa.gov/sign-here- glossary/en/ http://www.redorbit.com/news/space/1750308/magnetic_fields_play_larger_role_in_star_formation / http://www2.hesston.edu/Physics/StarsAmy/starspaper.ht m http://www.flashflashrevolution.com/vbz/showthread.php?p=368924 7 http://science.howstuffworks.com/how-are-stars- formed.htm http://science.howstuffworks.com/star6.ht m