Rapid Rotation and Nonradial Pulsations: κ-Mechanism Excitation of [CLC][ITAL]g[/ITAL][/CLC]-Modes in B Stars

Several classes of stars (most notably O and B main-sequence stars, as wellas accreting white dwarfs and neutron stars) rotate quite rapidly, at spinfrequencies greater than the typical g-mode frequencies. We discuss how rapidrotation modifies the $\kappa$-mechanism excitation and observability of g-modeoscillations. We find that, by affecting the timescale match between the modeperiod and the thermal time at the driving zone, rapid rotation stabilizes someof the g-modes that are excited in a non-rotating star, and, conversely,excites g-modes that are damped in absence of rotation. The fluid velocitiesand temperature perturbations are strongly concentrated near the equator formost g-modes in rapidly rotating stars, which means that a favorable viewingangle may be required to observe the pulsations. Moreover, the stability ofmodes of the same $l$ but different $m$ is affected differently by rotation. Weillustrate this by considering g-modes in Slowly Pulsating B-type stars as afunction of the rotation rate.Comment: 7 pages, including 3 figures; uses emulateapj.sty (included); accepted to ApJ Letter