On 05/01/2016 07:38, Poutnik wrote:
Hello,

I have noticed there is quite a lot of different star behaviours.

Are the star properties and behaviour
more or less determined by initial mass and evolution stage ?

To a first approximation yes.
Initial mass and age determine what you see.

Or are there a parallel evolution paths possible ?

I suppose being in binary system
can create other dimension to variability.

Dwarf nova binaries, cataclysmic variables and the like where matter
accretes from the first star to reach giant stage onto the other and
then vice-versa are about the only major exceptions.

http://www.star.le.ac.uk/~pae9/twitter/DNe.html

I recall a talk by one of the researchers in that field whimsically
titled "Can a degenerate white dwarf find lasting happiness in the arms
of a blue giant?" - spoiler alert sadly the answer is no.

How much is eventually in this context significant
difference in initial composition,
like stars of the 1st generation with initial cosmological composition,
versus later generations with some extra helium and heavier elements ?

There are visible differences in the absorption lines of early low
metalicity stars.

--
Regards,
Martin Brown