We report the discovery of the first variable extreme horizontal branch star in a globular cluster (omega Cen). The oscillation uncovered has a period of 114 s and an amplitude of 32 mmags. A comparison between horizontal branch models and observed optical colours indicates an effective temperature of 31,500+-6,300 K 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.
@article{arxiv.0812.2684,
title = {Discovery of a rapidly pulsating subdwarf B star candidate in omega Cen},
author = {S. K. Randall and A. Calamida and G. Bono},
journal= {arXiv preprint arXiv:0812.2684},
year = {2009}
}
Comments
5 pages, 7 figures; accepted for publication in A&A