Past exam of the astrophysics course of the University of Oxford / 2015 / 1 / b / ii / Solution

For the mixed pair, $M=11.4M_{\odot }$ and $\mu =(14/11.4)M_{\odot }=1.228M_{\odot }$. The prescribed instantaneous orbital decay timescale givesThe integrated ten-billion-year merger criterion instead gives $26.6$ h. Both are pre-disruption circular-orbit estimates; the final contact/capture process differs from that for two neutron stars.