Stars make Helium as they shine - so more with age.
Im no astrophysicist but an older star would consume more of its hydrogen over time in comparison to helium through its fusion process. Over time concetrations would change resulting in a higher helium to hydrogen ratio.
A star that fuses hydrogen into helium is called a main sequence star. This is the stage in a star's life cycle where it is converting hydrogen into helium through nuclear fusion in its core, resulting in the release of energy.
A star's position in the main sequence on the Hertzsprung-Russell diagram tells us its temperature, luminosity, and evolutionary stage. Stars in the main sequence are undergoing nuclear fusion in their core, converting hydrogen into helium. The more massive and brighter stars are found at the top left, while less massive and dimmer stars are at the bottom right of the main sequence.
A "main sequence star" is not really a type of star but a period in a stars life. When a star is in "main sequence" it is converting hydrogen into helium. It is then usually called a dwarf star. This is the longest period in a stars lifetime. Our Sun is a yellow dwarf in "main sequence".
A star's position on the main sequence indicates its mass, temperature, luminosity, and evolutionary stage. Stars fuse hydrogen into helium in their cores while on the main sequence. The more massive the star, the hotter, brighter, and shorter its lifespan.
Im no astrophysicist but an older star would consume more of its hydrogen over time in comparison to helium through its fusion process. Over time concetrations would change resulting in a higher helium to hydrogen ratio.
A star that fuses hydrogen into helium is called a main sequence star. This is the stage in a star's life cycle where it is converting hydrogen into helium through nuclear fusion in its core, resulting in the release of energy.
All stars that are converting hydrogen into helium via nuclear fusion are said to be on "main-sequence". See related question for more information
That's more or less the description of the so-called "main sequence". Those are the stars that get their energy by fusing hydrogen into helium.
A star's position in the main sequence on the Hertzsprung-Russell diagram tells us its temperature, luminosity, and evolutionary stage. Stars in the main sequence are undergoing nuclear fusion in their core, converting hydrogen into helium. The more massive and brighter stars are found at the top left, while less massive and dimmer stars are at the bottom right of the main sequence.
A "main sequence star" is not really a type of star but a period in a stars life. When a star is in "main sequence" it is converting hydrogen into helium. It is then usually called a dwarf star. This is the longest period in a stars lifetime. Our Sun is a yellow dwarf in "main sequence".
The star's mass. More mass will make the star hotter, and will increase the pressure in the center; this will make the star burn its fuel faster.When a star is on the "main sequence", it burns hydrogen-1, converting it into helium-4.
A star's position on the main sequence indicates its mass, temperature, luminosity, and evolutionary stage. Stars fuse hydrogen into helium in their cores while on the main sequence. The more massive the star, the hotter, brighter, and shorter its lifespan.
A "Main Sequence" star does not "really exist". The term "main sequence" refers to a period in a stars life when it is basically converting hydrogen into helium. Once it has consumed all of the hydrogen, a star will evolve out of main sequence into stellar remnants. The main sequence is a continuous and distinctive band that appear on plots of stellar colour versus brightness on the Hertzsprung Russell diagram. Our Sun is smaller and a little more yellow than most other main sequence stars, which are white. It will gradually run out of hydrogen fuel in another 5 billion years, at which point it will expand to become a red giant. After that it will dim, cool down, and fade into a white dwarf. See related question on the life of a star.
Main-sequence stars with mass less than 0.4M convert all of their mass into helium and then stop fusing. Their lifetimes last hundreds of billions of years, so none of these stars has yet left the main sequence. Core hydrogen fusion ceases when hydrogen in the core of a main-sequence star with more than 0.4M is gone, leaving a core of nearly pure helium surrounded by a shell where hydrogen fusion continues. Hydrogen shell fusion adds more helium to the star's core, which contracts and becomes hotter. The outer atmosphere expands considerably, and the star becomes a giant. Comments: I guess 0.4M means 0.4 solar masses. Usually the "M" has an extra little symbol next to it when it means this. Also I'm not sure that there's an exact number you can put on the division between these two types of star. I could argue with the details in the answer, but I have not got the time. Anyway the basic idea seems correct.
The Main Sequence stage.
Theoretically, in 5 billion years, the Sun will still be in the main sequence. 5.4 billion years (estimated) marks the end of main sequence, where it will be in the intermediary point between a main-sequence star and a post-main-sequence red giant, where it will slowly reach over 200 times it's current mass over the course of about a billion more years, at which point it would be classified as an official red giant and be fully burning helium-4 as a main source of fuel as well as burning a hydrogen shell it built up during the main-sequence. After that point it will eject most of its mass into a planetary nebula and slowly cool as a stellar remnant over the course of a few quadrillion years until it reaches 3K.