Discovery of a rapidly pulsating subdwarf B star candidate in Centauri *
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany e-mail: firstname.lastname@example.org,email@example.com
2 Istituto Nazionale de Astrofisica, Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone, Italy e-mail: firstname.lastname@example.org
3 Università di Roma “Tor Vergata”, Department of Physics, via della Ricerca Scientifica 1, 00133 Rome, Italy
Accepted: 26 November 2008
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 114 s and an amplitude of 32 mmag. A comparison between horizontal branch models and observed optical colours indicates an effective temperature of 31 500 ± 6300 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.
Key words: stars: horizontal-branch / stars: subdwarfs / stars: oscillations / Galaxy: globular clusters: general
© ESO, 2009