= Adiabatic orbital expansion under isotropic mass loss
{title2=$\mu a=\mathrm{constant}$}
Time averaging over a <Kepler orbit> gives $\langle\cos f\rangle=-e$, as follows from $dt=(1-e\cos E)dE/n$ and $\cos f=(\cos E-e)/(1-e\cos E)$. Consequently slow <isotropic stellar mass loss> preserves the secular <orbital eccentricity>. Conserved <specific angular momentum> then gives $\mu a=\mathrm{constant}$, so <pericentre>, <apocentre> and <semimajor axis> expand inversely with the remaining gravitational parameter.
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