Line profile variations caused by low-frequency nonradial pulsations of rapidly rotating stars

Line profile variations caused by low-frequency nonradial g-mode oscillations of a rotating star are presented. For a nonradial oscillation mode whose oscillation frequency in the corotating frame is comparable to or smaller than the rotation frequency, the latitudinal dependence of the oscillation amplitude deviates significantly from that for a nonrotating star. Rotation usually causes oscillations confined to a narrow equatorial belt as well as causing toroidal velocity fields. The concentration of the amplitude of the oscillation toward the equator leads to a reduction in the strength of the bumps in line profiles if the maximum velocity of nonradial pulsation is fixed. For the same normalization, the line profile variations due to the sectoral prograde mode are most visible, while those caused by retrograde waves are almost invisible due to a cancellation effect. The toroidal component generated by stellar rotation appreciably affects the line profile variation of some modes.