¹ Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK

Through the adoption of the so-called `traditional approximation', a new semi-analytical formula is derived for the light variations produced by low-frequency g modes in uniformly-rotating stars. The formula is used to examine the influence of rotation on the variability produced by stellar model representative of the slowly-pulsating B-type class.

It is found that, for all apart from prograde sectoral modes, the Coriolis force acts to trap pulsation within an equatorial waveguide. Toward rapid rotation and/or low pulsation frequency, this waveguide becomes so narrow that only a thin band around the stellar equator makes any appreciable contribution toward flux changes. As a result, unless viewed from near the poles, the variability exhibited by the star becomes very small, possibly explaining why recent photometric observations of rapidly-rotating stars have failed to find much evidence for the presence of low-frequency modes.

It is further demonstrated that the ratio between the variability amplitude in pairs of passbands depends, with the introduction of rotation, both on the azimuthal order of a mode, and on the location of the observer in relation to the star's rotation axis. This means that the standard photometric techniques used to identify modes in non-rotating stars cannot easily be applied to systems where rotation is significant.

Accepted by MNRAS
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