Question

a binary system of neutron stars, each with mass 2x Msun, what is the maximum period the system could have so that it will coalesce in 14 billion years?

Answer 1

The binary coalscence time is given by the formula

Here, the period is in hours

and the mass is in terms of solar masses.

The mass of each star is given by

2*Msun

The time for coalesce is given by

t = 14 billion years = 14*10^12 years

Using these in the formula

So,