# Finding Number of Stars that have Died

1. Sep 24, 2015

### astrofunk21

Hi everyone,

I am currently looking to calculate the amount of stars that die within a certain time-frame. I am trying to go about this using the Salpeter IMF to figure the distribution of star masses...

∫M⋅Φ(M)dM

From here I would need to use star mass to calculate the lifetime of stars as a function of mass...t(M). Then using this I would apply it somehow to the distribution to find out how many of those stars die for a given time (t +Δt).

Is this the right train of thought?

Edit:

Thinking about this more, I could also find the mass turnoff point at that time. From this can't I calculate how many stars are above that mass? That would give me how many stars have died up to that time? If this is all true, it must be difficult to make this a generalized formula...thoughts?

Last edited: Sep 24, 2015
2. Sep 24, 2015

### phyzguy

The first thing you will have to do is define "died". If a sun-like star has become a white dwarf, has it "died"? Or is it only dead when the white dwarf has cooled to the point where it no longer emits visible light? Or is it even dead then? It is still emitting longer wavelength radiation. How about a massive star that has gone supernova and left a neutron star behind. Has it "died"? The neutron start is still there. Once you have done this, you should be able to write down the star's lifetime as a function of mass. then your plan should work.

3. Sep 24, 2015

### astrofunk21

Thanks for the response. I should've clarified! Rather than "died" I should've said turned off the Main Sequence!

4. Sep 24, 2015

### phyzguy

Then that should be fairly straightforward. You should be able to find the main-sequence lifetime as a function of mass.