system will presumably evolve to a second (and last) CE event, according to the double-CE model via the $\gamma$ mechanism by @Nelemans00 [@Nelemans05]. In their scenario, at the start of the second CE event a giant donor has a mass of about $1.7-2.2\,M_\odot$ and the original primary star has already formed a WD with a mass of $\sim 0.35-0.55\,M_\odot$.

Common envelope via $\alpha$-formalism {#sec:example1}
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![ Orbital angular momentum $J$ and energy $E$ for a CE in a $2\,M_\odot + 0.5\,M_\odot$ binary ($r_\mathrm{d}=23\,R_\odot$ and $m_\mathrm{d,X}=0.337\,M_\odot$). The black star indicates the state of the binary at the onset of the CE. The solid line (red) shows the Keplerian $E_\mathrm{orb}- J_\mathrm{orb}$ relation for the final binary assuming that the mass of post-CE remnant consists of all the RG mass that was originally contained within the final Roche lobe ($m_\mathrm{RL}$), in other words, the maximum possible remnant mass for this orbit. The shaded region contains Keplerian orbits for core masses bounded by $m_\mathrm{c,min} < m_\mathrm{d, c} < m_\mathrm{c, max}$ (see the text). A final state of the post-CE binary must lie within this area. The dashed lines (blue) trace the minimum energy expenditures to release the envelope with, for $\lambda$ calculated using the 