2009A&A...494.1053R

We report the discovery of the first variable extreme horizontal branch star in a globular cluster (ω Cen). The oscillation uncovered has a period of 114s and an amplitude of 32mmag. A comparison between horizontal branch models and observed optical colours indicates an effective temperature of 31500±6300K for this star, placing it within the instability strip for rapidly oscillating B subdwarfs. The time scale and amplitude of the pulsation detected are also in line with what is expected for this type of variable, thus strengthening the case for the discovery of a new subdwarf B pulsator.