Fig. 2

Solid lines represent the locations of the instability boundary for \(\mu = 0.2, 0.3, 0.4\) binary systems. The dashed line represents the inner cavity size and critical radius for a \(\mu =0.3\) binary system. The location of unstable boundary is always larger than the disk inner edge for any \(e_{\mathrm {bin}}\). \(r_{\mathrm {crit}}\) and \(r_{\mathrm {cav}}\) are calculated using Eqs. 1 and 2, respectively