AS102 Study Guide - Final Guide: Carbon-Burning Process, Oxygen-Burning Process
Document Summary
In a relatively short time (100-200,000 years) the he fusion process is finished and the carbon core begins to collapse under the continuing influence of gravity (gravity wins yet again!). The result is an increased temperature and density and a helium-burning shell forms between the core and the hydrogen-burning shell; the star swells again. This time, however, because of the greater mass of the core the temperature rises to the point where carbon fusion can take place (about 1 billion k!). Some of the fusion reactions result in increasingly more massive elemental atoms being formed. Carbon fuses with he to form oxygen, etc. or c fuses with o to form. Silicon and two si atoms fuse to form iron. Each time the core depletes the elements it is fusing, it shrinks and heats until it becomes hot enough for a new fusion reaction to begin.
