Journal Article

Fortnightly fluctuations in the O−C diagram of CS 1246*

B. N. Barlow, B. H. Dunlap, J. C. Clemens, D. E. Reichart, K. M. Ivarsen, A. P. LaCluyze, J. B. Haislip and M. C. Nysewander

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 414, issue 4, pages 3434-3443
Published in print July 2011 | ISSN: 0035-8711
Published online July 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.18645.x
Fortnightly fluctuations in the O−C diagram of CS 1246*

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Dominated by a single, large-amplitude pulsation mode, the rapidly pulsating hot subdwarf B star CS 1246 is a prime candidate for a long-term O−C diagram study. We collected nearly 400 h of photometry with the 0.41-m Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes over a time-span of 14 months to begin looking for secular variations in the pulse timings. Interestingly, the O−C diagram is dominated by a strong sinusoidal pattern with a period of 14.1 d and an amplitude of 10.7 light-seconds. Underneath this sine wave is a secular trend implying a decrease in the 371.7-s pulsational period of , which we attribute to the evolution of the star through the Hertzsprung–Russell diagram. The sinusoidal variation could be produced by the presence of a low-mass companion, with m sin i≃ 0.12 M, orbiting the subdwarf B star at a distance of 20 R. An analysis of the combined light curve reveals the presence of a low-amplitude first harmonic to the main pulsation mode.

Keywords: stars: individual: CS 1246; stars: oscillations; subdwarfs

Journal Article.  5861 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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