# Calculating the expected lifespan for a binary system

I’m doing some research work on finding a correlation between the mass of binary stars and their lifespan. I have methods to find the mass, and that department seems to be going fine, but is there a way I can determine the lifespan of the star? If someone knows how to calculate the lifespan (in years) for a binary system that would be amazing. Additionally, I am open to applying the Chandrashekhar limit on a binary system, I would just appreciate a few pointers on how exactly to apply it. Finally, if someone has another metric for determining the lifespan of a star, I would be open to researching that as well. Any help for this topic is appreciated, but I must keep calculations for mass in my paper, anything else can be modified. As per defining what "expected lifetime" is exactly, for detached binaries, it would be till one of the stars evolves into a neutron/white dwarf/ blackhole and eventually consumes the other star. For contact and semi-detached, I was thinking until they both collide. Any help would be much appreciated!

a binary star system will last until either:

The two stars spiral closer together, collide, and merge, forming a single star.

or:

Gravitational interactions between the stars and with passing stars and other objects cause the stars to move apart until they separate into two single star systems instead of one binary star system.

Depending on various factors such as the masses and initial separation of the star, either process might take mere millions of years or many trillions of years.

Depending on the initial masses of the two stars in a binary it might take mere millions or many trillions of years for each star to go through the main sequence phase, become a red giant, and eventually become a white dwarf, neutron star, or black hole.

If the two stars are close enough, there may be exchanges of mass between them, which will change the timetables of their stellar development.

And that is about all that anyone can say about binary stars in general.

An expert in stellar evolution should be able to calculate the expected lifetime of a specific binary star system with information about the masses and chemical compositions of the two stars, their initial orbital parameters, where in space the system is, and so on.