Which element do all stars start out fusing?

Which element do all stars start out fusing?

• A. Hydrogen
• B. Helium
• C. Carbon
• D. Iron

Answer: (A)

Stars begin life by fusing hydrogen in their cores. The collapse of a gas cloud heats the center to extremely high temperatures, enough to make hydrogen nuclei fuse together and release energy. That energy provides the pressure to balance gravity, keeping the star stable during the main-sequence phase. Helium is produced from hydrogen, but the star isn’t powered by fusing helium at the start because the core isn’t hot enough yet to fuse helium. Heavier elements like carbon and iron require even higher temperatures and more advanced stages of stellar evolution, so they don’t power stars in their initial phase. In short, hydrogen fusion is the first and fuel for the long main-sequence life of most stars.

Stars begin life by fusing hydrogen in their cores. The collapse of a gas cloud heats the center to extremely high temperatures, enough to make hydrogen nuclei fuse together and release energy. That energy provides the pressure to balance gravity, keeping the star stable during the main-sequence phase. Helium is produced from hydrogen, but the star isn’t powered by fusing helium at the start because the core isn’t hot enough yet to fuse helium. Heavier elements like carbon and iron require even higher temperatures and more advanced stages of stellar evolution, so they don’t power stars in their initial phase. In short, hydrogen fusion is the first and fuel for the long main-sequence life of most stars.