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Be stars are main-sequence massive stars with emission features in theirspectrum, which originates in circumstellar gaseous discs. Even though theviscous decretion disc (VDD) model can satisfactorily explain mostobservations, two important physical ingredients, namely the magnitude of theviscosity ($\alpha$) and the disk mass injection rate, remain poorlyconstrained. The light curves of Be stars that undergo events of disc formationand dissipation offer an opportunity to constrain these quantities. A pipelinewas developed to model these events that uses a grid of synthetic light curves,computed from coupled hydrodynamic and radiative transfer calculations. Asample of 54 Be stars from the OGLE survey of the Small Magellanic Cloud (SMC)was selected for this study. Because of the way our sample was selected (brightstars with clear disc events), it likely represents the densest discs in theSMC. Like their siblings in the Galaxy, the mass of the disc in the SMCincreases with the stellar mass. The typical mass and angular momentum lossrates associated with the disk events are of the order of $\sim$$10^{-10}\,M_\odot\,\mathrm{yr^{-1}}$ and $\sim$$5\times 10^{36}\, \mathrm{g\, cm^{2}\,s^{-2}}$, respectively. The values of $\alpha$ found in this work are typicallyof a few tenths, consistent with recent results in the literature and with theones found in dwarf novae, but larger than current theory predicts. Consideringthe sample as a whole, the viscosity parameter is roughly two times larger atbuild-up ($\left\langle\alpha_\mathrm{bu}\right\rangle = 0.63$) than atdissipation ($\left\langle\alpha_\mathrm{d}\right\rangle = 0.26$). Further workis necessary to verify whether this trend is real or a result of some of themodel assumptions.

The life cycles of Be viscous decretion discs: fundamental disc parameters of 54 SMC Be stars