What happens when the hydrogen in the star is completely converted to helium?
As the hydrogen gets depleted the outward force of the fusion reaction starts diminishing and the inward force caused by the star’s gravity gains the upper hand. Consequently, the star begins to shrink in size as well as increase in brightness. Its colour also changes from red to white.
How much energy is produced by the helium fusion reaction?
Almost 95% of the total energy that a star can generate through fusion reactions is generated through hydrogen fusion. The fusion of helium and heavier elements will account for just over 5% of the total energy that a star can generate.
How long is the fusion reaction in a star likely to go on?
Once the hydrogen and the helium fusions stop due to the exhaustion of their supply, the fusion reactions may continue to produce heavier elements but energy generated by these reactions is rather negligible. The fusion reaction will continue until all the matter in the star is completely converted to the element iron. The star will then radiate energy only by depleting its stock of accumulated internal energy.
Does the fusion reaction in a star always priced to the iron stage?
Generally, the fusion reaction in all stars will proceed to the helium fusion stage. However, the extent to which it proceeds beyond this stage depends on the amount of pressure and temperatures developed at the core of the star. The larger the star the larger will be the number of fusion stages it will go through before the fusion reaction stops.
How massive must a star be to completely convert into iron?
Foe a star to completely convert into iron, it must be at least 30 times as massive as the Sun.
Why does the fusion reaction stop when all the matter is converted into iron?
The pressure created in the cores of ordinary stars is insufficient to continue the fusion reaction beyond the element iron.