Evolution of the disk of π Aqr: from near-disappearance to a strong maximum

Abstract Some Be stars display important variability of the strength of the emission lines formed in their disk. This is notably the case of π  Aqr. We present here the recent evolution of the Be disk in this system thanks to spectra collected by amateur spectroscopists since the end of 2013. A large transition occurred: the emission linked to the Be disk nearly disappeared in January 2014, but the disk has recovered, with a line strength now reaching levels only seen during the active phase of 1950–1990. In parallel to this change in strength occurs a change of disk structure, notably involving the disappearance of the strong asymmetry responsible for the V / R modulation.