How do stars in our galaxy differ from stars in other galaxies?

1 Answer
Jan 26, 2016

They're similar but distant galaxy have younger stars with less heavy elements.


There's not many ways in which stars can differ. The basic ones are the star's mass and the star's fraction of heavy elements (or metals, which is what an astronomer calls the elements heavier than Helium.)

In terms of mass, the stars in our galaxy have a specific range of masses called the initial mass function. The IMF does vary with the age of the galaxy, however, so more distant (and thus younger) galaxies will have a slightly different distribution of star masses.

As for the chemical composition of stars in other galaxies, intuitively more distant galaxies will have stars with less elements heavier than Helium. This will slightly affect their lifespan and the way they burn hydrogen and Helium but overall this is a 1-10% effect on stellar age.

Finally, galaxies 8 or so billion years away had the largest rate of forming stars. Our milky way in comparison makes stars hundreds of times less efficiently