2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/9546The long-term variation of the H$α$ line in $α$ Eri has 14-15 years cyclic \bbe phase transitions. The disc formation time scales, interpreted as the periods during which the H$α$ line emission increases from zero to its maximum, agree with the viscous decretion model. On the other hand, the time required for the disc dissipation ranges from 6 to 12 years which questions the viscous disc model predictions.Astrophysicstext