Question

What process do main sequence stars use to produce energy?

Answer 1

Main sequence stars produce energy by fusing hydrogen into helium.

Explanation:

Fusion reactions which fuse 4 hydrogen nuclei into a helium nucleus generates the energy in main sequence stars. There are two ways by which this can happen.

Smaller stars like the Sun use the proton proton chain reaction. First of all the strong nuclear force fuses two protons into a highly unstable diproton.

`"_1^1H` `+ "_1^1H` `-> "_2^2He`

Most of the diprotons formed decay back into two protons. Occasionally the weak nuclear force converts a proton into a neutron to form deuterium, a positron and an electron neutrino.

`"_2^2He` `->"_1^2H` `+e^(+)+nu_e`

The deuterium then fuses with a proton for form helium-3.

`"_1^2H` `+ "_1^1H` `-> "_2^3He`

Two helium-3 nuclei then fuse to form the highly stable helium-4 and two protons.

`"_2^3He` `+ "_2^3He` `-> "_2^4He` `+2"_1^1H`

In the case of larger stars, they fuse hydrogen into helium using the Carbon-Nitrogen-Oxygen (CNO) cycle.

First carbon-12 fuses with hydrogen for form nitrogen-13. The nitrogen-13 then decays by the weak force into carbon-13

`"_6^12C` `+ "_1^1H` `-> "_7^13N`
`"_7^13N` `->"_6^13C` `+e^(+)+nu_e`

The carbon-13 fuses with hydrogen for form nitrogen-14.

`"_6^13C` `+ "_1^1H` `-> "_7^14N`

The nitrogen-14 fuses with hydrogen to produce oxygen-15. The oxygen-15 then decays by the weak force to produce nitrogen-15.

`"_7^14N` `+ "_1^1H` `-> "_7^15O`
`"_8^15O` `->"_7^15N` `+e^(+)+nu_e`

Finally the nitrogen-15 fuses with hydrogen and then undergoes alpha decay to produce carbon-12 and helium-4.

`"_7^15N` `+ "_1^1H` `-> "_6^12C` `+"_2^4He`

Each of the reactions in both processes produce energy.