Armagh Observatory Preprint Series No. 307

Constraints on the dimensions of pulsating helium stars V652 Her and LSS 3184

Authors: C.S.Jeffery, H.Saio

Journal: 1999, MNRAS submitted

Abstract. For pulsating helium stars, the luminosity-to-mass ratio can be measured both from the absorption-line spectrum and from the pulsation properties. In an early draft, a recent spectroscopic study suggested that V652 Her might have a mass lower than previously measured, prompting us to calculate linear pulsation models for low mass helium stars. By comparing the twin constraints imposed by the neutral helium line profiles and the pulsation period, we find that the observed spectroscopic and pulsation properties of V652 Her remain in excellent agreement with the original value of 0.7 M_sun, subject to verification of the radius measurement. Consequently we demonstrate that the dual observations of pulsation period and neutral helium line profiles combine to place limits on the mass and effective temperature of pulsating helium stars. Applying this procedure to LSS 3184 we show that its properties should be Teff~26 500 K, M>0.53 M_sun, R>1.7 R_sun.

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