is a minimum amount of energy that needs to be extracted. Nonetheless, for a properly computed $\lambda$, final orbital separations can vary over a factor of 10, depending on the choice of core mass. The whole range of possible states is now bounded by the blue dashed line to the bottom, the solid red line to the top and the shaded red area. When the CE is initialised at a different giant radius (*i.e.*, at a different orbital period), and accordingly a different $m_\mathrm{d,X}$, the picture is qualitatively similar, although the uncertainty that is introduced by the core-mass definition could vary.

Common envelope via $\gamma$-formalism  {#sec:example2}
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We now construct an example that fits the $\gamma$-parametrisation introduced in @Nelemans00 and further studied in @Nelemans05, and show that it is not robust against small changes in binary parameters. The latter study determined the range of values for $\gamma$ to be between $\sim 1.2$ and up to $4$ in the first episode of the MT and between $\sim 0.5$ and $3$ in the last episode of the MT, with the most likely value of $\gamma\approx1.5$ — *i.e.*, every gram of the escaped envelope material carries away 1.5 times the average specific angular 