Total outer belt mass required if scattering by a chain of equal mass planets, as shown in Fig. 9, or detailed in Table 3, is to replenish an exozodi inside of 1 AU around Vega at the required rate of 10^-9 M_⊕ / yr. Each cross represents an individual scattering event shown in Fig. 9 and scaled by a factor of to account for Vega’s stellar mass. Vega is plotted by the diamond at its age of 455 ± 13 Myr (Yoon et al. 2010) and with an outer belt mass of 46.7 M_⊕, as found by the modelling of Müller et al. (2010). No error bars are quoted on the mass, however, its model dependence should be noted.