Variations of the amplitudes of oscillation of the Be star Achernar

TL;DR

This study analyzes five years of photometric data of Achernar, revealing significant amplitude variations in its main oscillation frequencies, which may be linked to stellar outbursts or cycles.

Contribution

It provides detailed analysis of amplitude variations in Achernar's oscillation frequencies over five years, a novel long-term observational study.

Findings

Amplitude of 0.725 c/d frequency varies by up to a factor of eight.

Two main frequencies identified at 0.775 c/d and 0.725 c/d.

Amplitude variations potentially linked to stellar outbursts or cycles.

Abstract

We report on finding variations in amplitude of the two main oscillation frequencies found in the Be star Achernar, over a period of 5 years. They were uncovered by analysing photometric data of the star from the SMEI instrument. The two frequencies observed, 0.775 c/d and 0.725 c/d, were analysed in detail and their amplitudes were found to increase and decrease significantly over the 5-year period, with the amplitude of the 0.725 c/d frequency changing by up to a factor of eight. The nature of this event has yet to be properly understood, but the possibility of it being due to the effects of a stellar outburst or a stellar cycle are discussed.