Variations of the amplitudes of oscillation of the Be star Achernar

Authors


E-mail: goss@bison.ph.bham.ac.uk

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 yr. They were uncovered by analysing photometric data of the star from the Solar Mass Ejection Imager (SMEI) instrument. The two frequencies observed, 0.775 and 0.725 d−1, were analysed in detail and their amplitudes were found to increase and decrease significantly over the 5-yr period, with the amplitude of the 0.725 d−1 frequency changing by up to a factor of 8. 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.

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