[Robcat (OP)]

Has anyone worked out how many Suns become active ( in our galaxy) in say one earth year as against how many Suns die by the known possible number of methods.

[evan_au]

This NASA estimate suggests about 7 new stars per year, formed from about 4 solar masses of gas and dust. That suggests that the average star is smaller and dimmer than the Sun.
http://www.nasa.gov/centers/goddard/news/topstory/2006/milkyway_seven.html

The same article suggests that our galaxy has a supernova about every 50 years.

A lot of small stars (<1.4 solar masses) don't end with a dramatic event, but end up as cool cinders when fusion stops and they eventually cool down. At what point do you say that the star is "dead"?

[Robcat (OP)]

I was thinking of black hole in addition to see how the galaxy balance is.
IE if we gain stars overall or are some galaxies in a growth path

It's a sort of Suns can be created and destroyed but just change form.

[evan_au]

Many galaxies show signs of having collided in their past; when their dust clouds smash into each other, they can trigger a "starburst" - many new, hot stars; typically 100 per year, in extreme cases, perhaps 1000 per year.
See: https://en.wikipedia.org/wiki/Galaxy_merger#Description

Our galaxy is expected to collide with the Andromeda galaxy in about 5 billion years - it should be quite spectacular, but I don't expect to be here to see it...