| Issue |
A&A
Volume 494, Number 3, February II 2009
|
|
|---|---|---|
| Page(s) | 1053 - 1057 | |
| Section | Stellar structure and evolution | |
| DOI | https://doi.org/10.1051/0004-6361:200811266 | |
| Published online | 11 December 2008 | |
Discovery of a rapidly pulsating subdwarf B star candidate in 
Centauri
*
1
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany e-mail: srandall@eso.org,acalamid@eso.org
2
Istituto Nazionale de Astrofisica, Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone, Italy e-mail: bono@mporzio.astro.it
3
Università di Roma “Tor Vergata”, Department of Physics, via della Ricerca Scientifica 1, 00133 Rome, Italy
Received:
31
October
2008
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
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