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

## TL;DR

This paper documents the dramatic evolution of pi Aqr's circumstellar disk over recent years, highlighting its near-disappearance and subsequent recovery to levels seen in historical active phases, along with structural changes.

## Contribution

It provides a detailed observational record of pi Aqr's disk evolution using amateur spectra, revealing a significant transition and structural changes in the disk.

## Key findings

- Disk emission nearly disappeared in 2014
- Disk recovered to active phase levels
- Disappearance of V/R asymmetry

## Abstract

Some Be stars display important variability of the strength of the emission lines formed in their disk. This is notably the case of pi 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.