[samtheman]

How can some stars only last a few millions of years, but many stars last many billions of years?
—
Size matters.

The smaller you are the more longevity you have.

Some red dwarves will burn their fuel efficiently over TRILLIONS of years.

Blue giants gobble up their gas with maximum inefficiency and only last millions.

But that’s good. When they explode, they scatter metals.

[Moonman62]

Some red dwarves will burn their fuel efficiently over TRILLIONS of years.

...

Due to the almost complete burning of hydrogen due to convection.

Red dwarfs are theorized to evolve into blue dwarfs. There are no blue dwarfs yet. Not even close.

[ETL]

Size matters. The smaller you are the more longevity you have.

Not necessarily "size", but "mass". There are huge red giant stars that are among the coolest stars.

[ETL]

Size matters. The smaller you are the more longevity you have.

Not necessarily "size", but "mass". There are huge red giant stars that are among the coolest stars.

[ETL]

Stars come in various colors, hottest ones being blue. Red and orange stars come next on the temperature scale, then yellow. Same thing going on with a stove flame. They're coolest at the 'tips' where the air helps lower the temp. Blue hot at the base.

[ETL]