Discovery of a rapidly pulsating subdwarf B star candidate in omega Cen

Abstract

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.

arXiv comment5 pages, 7 figures; accepted for publication in A&A

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Cited by in corpus (6)

• A survey for pulsating subdwarf B stars with the Nordic Optical Telescope
• SHOTGLAS I: The ultimate spectroscopic census of extreme horizontal branch stars in $\omega$ Centauri
• A search for variable subdwarf B stars in TESS Full Frame Images -- I. Variable objects in the southern ecliptic hemisphere
• A Helium-Carbon Correlation on the Extreme Horizontal Branch in $\omega$ Centauri
• Pulsating hot O subdwarfs in Omega Cen: mapping a unique instability strip on the Extreme Horizontal Branch
• Just how hot are the $\omega$ Centauri extreme horizontal branch pulsators?