Armagh Observatory Preprint Series No. 305

The pulsating hydrogen-deficient star LSS3184 (BX Cir)

Authors: D.Kilkenny, C.Koen, C.S.Jeffery, N.C.Hill, D.O'Donoghue

Journal: 1999, MNRAS in press

Abstract. We present extensive photometry and spectroscopy of the extremely hydrogen-deficient star, LSS3184, recently discovered to be a rapid variable (period ~0.1066d) strkingly similar to V652 Her. Over 95 hours of photometry confirms the reported variability, which is of rather low amplitude (Delta V~0.03 mag), defines the light curve with greater precision and establishes a much more accurate ephemeris (period ~ 0.1065784d) to form a basis for detecting period change. Attention is drawn to the usefulness of a period finding technique which fits harmonic components to the photometric observations. Spectrsocopy shows a peak-to-peak variation in radial velocity of about 30 km/s which, when combined with the photometric observations, confirms the pulsational nature of the variability and strongly indicates that the pulsations are radial in nature.

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