 Solution

ID: past-exam-of-the-astrophysics-course-of-the-university-of-oxford/2015/1/b/ii/solution

For the mixed pair,

M = 11.4 M_{⊙}

and

μ = (14/11.4) M_{⊙} = 1.228 M_{⊙}

. The prescribed instantaneous orbital decay timescale gives

A_{m a x} = 5.53 \times 1 0^{9} m, P_{m a x} = 18.4 h .

The 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.

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