View Full Version : The Sun

2019-Feb-14, 11:50 PM

Our Star the Sun is a second generation Star and it converts Hydrogen in to Helium..

But if stars convert hydrogen into helium how come there was enough hydrogen left after the first generation star finished burning all of it's fuel
to start a new second generation star ? I mean, that is a lot of hydrogen left over.. ?

2019-Feb-14, 11:56 PM
Most of the original Hydrogen in our galaxy has never been in a star yet. The output of Supernovae adds some content to the clouds, but they are still mostly Hydrogen.
Side note: it is hard to say what generation our Sun is from, but it is likely that the stars that exploded about 5 billion years ago to help add heavy elements to our protosolar nebula were at least 2nd generation.

2019-Feb-15, 01:10 AM
In addition to what antoniseb said about most hydrogen in the universe has still not collapsed into a star, medium to high mass stars do NOT convert all of their hydrogen into helium by the time they die. If I remember correctly, our sun will only convert about 10% of it's hydrogen into helium by the time it dies, and I believe it's an even lower % for the really high mass stars. Only low mass red dwarfs will consume 100% of their hydrogen, and that takes trillions of years.

2019-Feb-15, 04:58 PM
Also, it may help to know that stellar cores, where fusion occurs, are often < 1/60th the volume of the star.